2. Benign osteoblastoma - NEOPLASMS OF THE MUSCULOSKELETAL TISSUES

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NEOPLASMS OF THE MUSCULOSKELETAL TISSUES

Oleh

Dr. HARI TJAHJONO WAHONO, FICS, SpOT, FWPOA

(Ahli Bedah Orthopaedi dan Traumatologi)

  

RSD SIDOARJO

Neoplasms of the musculoskeletal tissues meliputi :

  1. Primary Neoplasms of bone

  2. True Primary Neoplasms of bone

  3. Mertaststic Neoplasms in Bone

  

4. Specific Primary Neoplasms and neoplasms- Like Lesions of Synovial Joint,

Bursae and Tendon Sheaths

  5. Non – neoplastic Lesion of Synovial Membrane Definition of Terms

  The term tumor (which is often loosely used to describe any localized swelling, or

  

lump) seems less precise than the term neoplasms or new growth, which refers to a new

and abnormal formation of cell, a process that progresses and continues to progress,

  throughout the life of the patient, unless some type of therapy intervenes. Thus, succeeding generations of neoplasms cells continue to devide by mitosis more

  

rapidly than do normal cells of the particular tissue and consequently produce a

progressive lesion; this explains the presence of excessive numbers of mitotic figure in

rapidly growing neoplasms. Neoplastic cells demonstrate ability to initiate independent

  growth in distant sites (metastases), the neoplasms is malignant and referred to as cancer.

  

Primary neoplasms of a given structure arise from cells that are normally “local

inhabitants” of that structure, whereas secondary neoplasms arise from cells that are “

outside invaders” from elsewhere.

The primary lesions may be divided into the following groups : osteogenic,

chondrogenic, collagenic and myelogenic. Turthermore, in each group there may be

  reactive lesions (which are not neoplasms), hamartomas (which many consider to be

  

“benign neoplasms”) and true neoplasms (some of which wre potentially malignant

and others of which are frankly malignant).

  Classification (Aegerter, 1968)

  I. Reactive Bone Lesions :

  A. Osteogenic : 1. Osteoid Osteoma

  2. Benign osteoblastoma

  B. Collagenic : 1. Subperiosteal cortical defect

  2. Non-osteogenic fibroma II. Hamartomas Affecting Bone

  A. Osteogenic : 1. Osteoma : 2. Osteochodroma

  B. Chondrogenic : Enchodroma

  C. Collagenic : 1. Angioma

  2. Aneurysmal bone cyst

  III. True Neoplasms of Bone

  A. Osteogenic : 1. Osteosarcoma

  2. Parosteal sarcoma

  3. Osteoclastoma (Giant Cell Tumor)

  B. Chondrogenic : 1. Benign chondroblastoma

  2. Chondromyxoid fibroma

  3. Chondrosarcoma

  C. Collagenic : 1. Fibrosarcoma

  2. Angiosarcoma

  D. Myelogenic : 1. Plasma cell myeloma (multiple Myeloma)

  2. Ewing’s tumor

  3. Reticulum cell sarcoma

  4. Hodgkin’s disease

  Merupakan reactive bone lesion, klinis terdapat persistent pain, biasanya pada children dan adolescent, khususnya pada laki-laki, pendeteksinya pada lower limb, femur, tibia. Jarang tumbuh dan biasanya ukuran diameternya kurang dari 1 cm, kadang besar. Nyerinya hilang dengan pemberian analgesic, bila dekat sendi bisa terjadi effusion, atropi atau sekitarnya. Harus dibedakan dengan chronic osteomyelitis, walaupun ini self limiting, tapi bila nyeri terus mungkin perlu di operasi.

  Osteoid Osteoma pada Femur

  BENIGN OSTEOBLASTOMA (Giant Osteoid osteoma)

  Biasanya terdapat di vertebra atau tulang lain, lebih besar dari osteoid osteoma, rasa nyeri hilang dengan di operasi.

  Benign osteoblastoma pada humerus

  OSTEOCHODROMA (Osteocartilaginous Exostoses)

  Merupakan tumor jinak, suatu pertumbuhan yang abnormal pada daerah metaphyse di tulang panjang dari anak yang sedang tumbuh, disini terjadi kegagalan remodeling dari tulang. Terdapat pertumbuhan yang abnormal dari tulang dan cartilage, gejala klinis terdapat tumor dengan local sweeling atau lump. Biasanya terdapat pada daerah metaphyse dari lower end of femur, upper end of tibia, upper end of humerus, kebanyakan pada actively growing ends of long bone, bila terjadi di banyak tempat disebut diaphyseal aclasis (multiple osteocartilaginous exostoses). Dengan tumbuh panjangnya tulang maka tangkai tumor ini dekat epiphyseal plate sedang ujungnya didaerah diaphyse. Bisa berubah jadi malignant kira-kira pada 1% dari kasus osteochondroma dan angka lebih tinggi pada yang multiple gejala klinis biasanya terdapat benjolan tampan rasa nyeri didaerah metaphyse tulang panjang. Tidak semua osteochondroma memerlukan terapi, kecuali bila menimbulkan keluhan maka perlu dilakukan operasi excise.

  Osteochodroma pada Tibia proximal dan Femur distal

  Terdapat banyak pada phalanges, metacarpal, metatarsal bila terjadi di banyak tempat disebutenchondromatosis (Ollier’s dyschondroplasia), terdapat pertumbuhan lesi absorsi bagian dalam dari cortek dan terdapat subperiosteal reavtive bone ke outer surface. Bisa berubah jadi chondrosarcoma. Terapi dengan curretase dan bone graft.

  Enchondroma pada phalanx medius digiti

  OSTEOSARCOMA

  Adalah tumor ganas, timbul dari primitive cell (poorly differentiated) didaerah

  

metaphyse tulang panjang pada dewasa muda, merupakan tumor primer tulang,

  merupakan tumor ganas terbanyak kedua setelah multiple myeloma. Secara genesis berasal dari osteoblastic primitive mesenchimal cells Terbanyak terletak pada femur distal, tibia proximal atau fibula, humerus proximal.

  

Tumbuh dengan cepat terjadi destruksi, bisa terjadi fraktur patologi. Terdapat

Codman’s triangle (elevasi dari periosteum pada foto rontgen). Kombinasi antara

  reactive bone dan neoplastik bone pada sepanjang pembuluh darah terlihat sebagai

  

“sunburst” appearance. Pada 50% dari kasus bisa metastase ke paru, gejala klinis tumor

  tumbuh dengan cepat, mula – mula terdapat rasa nyeri ringan kemudian sedang selanjutnya nyeri sekali dan menetap. Kulit terasa hangat, banyak pembuluh darah vena yang dilatasi. Diagnosa dengan biopsi, prognosa jelek karena kebanyakan sudah metastase ke paru pada stadium awal.

  Osteosarcoma Femur distal dan fraktur patologis

  OSTEOCLASTOMA (Giant Cell Tumor of Bone)

  Tumbuh didaerah epiphysis tulang panjang, setelah epiphyseal plate menutup, terdapat pada radius distal, tibia proximal, femur distal, biasanya exten ke articular cartilage. Tulang destruksi, cancellous dan cortical bone diresorbsi dari dalam, terdapat expanded periosteum deposit bone cenderung jadi gabas, pada mikroskopis terlihat a vascular

  

network of stromal cells dan sejumlah banyak multinucleated giant cells. Gejala klinis

  penderita mengeluh local pain, kadang ada gangguan sendi Radiology terdapat local destruksi daerah epiphyse seperti gelembung sabun. Prognosa jelek.

  Giant cell tumor pada radius distal Tumbuh dari bone marrow tulang, biasanya pada usia diatas 40 tahun, terdapat pada

  

spine, pelvis, skull, terasa nyeri, terdapat destruksi tulang bisa terjadi fraktur patologis

  tulang, Terdapat banyak gamma globulin protein di excresi lewat urine, protein ini di produksi oleh plasma cell. Dan ini disebut Bence-Jone protein yang terdapat sekitar 50% dari kasus. Diagnosa dengan needle aspiration bipsi dari marrow crista illiaca atau sternum. Prognosa jelek

  EWING’S SARCOMA (EWING’S TUMOR)

  Merupakan tumor ganas tumbuh cepat dari primitive cell bone marrow, terjadi pada

  

umur muda, biasanya pada medullary cavity tulang panjang. Ini merupakan tumor

  ganas terbanyak ketiga setelah multiple myeloma dan osteosarcoma terdapat banyak pada anak dewasa muda di tulang femur, tibia, ulna, metatarsals. Tumbuh dari medullary cavity kemudian perforasi ke cortex dari shaft dan elevasi dari periosteum, repeated elevasi dari periosteum timbullah “Union Skin”. Metastase ke paru dan tulang tulang lain. Mikroskopis terdapat poorly differentiated round cells of marrow origin. Metastase lewat blood stream dan menimbulkan gejala sistemik seperti slight fever, moderate leucocitosis dan peningkatan laju endap darah, dan pada tumor terdapat avascular necrosis dari tulang. Juga terdapat keluhan nyeri progresif dari penderita. Deferential diagnose dengan chronic osteomyelitis dan eosinophylic granuloma, diagnose pasti dengan biopsy. Prognose jelek, angka kematian 95% dari kasus dan terjadi beberapa tahunpertama setelah diagnose dibuat.

  Ewing’s sarcoma pada femur

  Menyebar dari primer carcinoma lewat aliran darah, limfe atau secara langsung, biasanya terdapat pada vertebra, pelvis, ribs dan proximal tulang panjang dari limbs. Pada umumnya tumor primer berasal dari breast, prostate, lung dan ginjal. Biasanya gambaran tulang terlihat destruktif, dan osteolytic metastase, kadang

  

osteoslerotic metastases. Keluhan penderita terdapat rasa nyeri dan kadang terdapat

  Pertama perlu diagnose yang akurat Benign neoplasma dan no malignant lain (jinak) biasanya dengan excise curettement dan bone grafting.

  Sedangkan yang malignant biasanya dilakukan perbaikan keadaan umum, amputasi, radiasi cytotoxic drugs dan obat paliatip yang lain. Prinsip pembedahan bisa dilakukan menurut Surgical Staging dari Enneking

Overview

  The prognosis of patients with musculoskeletal tumors has improved markedly because of the advent of new chemotherapeutic drugs and regimens and as a result of advances in imaging and surgical techniques. Limb-salvage operations can currently be performed with better outcomes, while in the past, limbs with tumors were treated only with amputation. (See the images below.)

  Frontal radiograph in a 9-year-old with trauma to the left knee shows a well-defined, cortically-based lesion with sclerotic margins, situated on the lateral aspect of the left upper tibial metaphysis. The lesion has the typical appearance of a fibrous cortical defect. Enneking stage 0. rontal radiograph in a 10-year- old boy with pain of the left upper limb shows a well-defined, loculated, centrally located lesion in the left humeral metaphysis. Overlying cortical thinning is noted. The lesion has the typical appearance of a unicameral bone cyst. Enneking stage II.

  puted tomography (CT) scan of the lungs shows Accurate preoperative surgical staging of musculoskeletal tumors is currently possible because of advanced imaging techniques, which is important because the images provide prognostic information and aid clinicians in choosing the most appropriate treatment option for the patient

Surgical Staging of Bone Tumors

  The aims of surgical staging are to determine the surgical margins of resection and to facilitate interinstitutional and interdisciplinary communication regarding treatment data and results The Enneking system for the surgical staging of bone and soft-tissue tumors is based on grade (G), site (T), and metastasis (M) and uses histologic, radiologic, and clinical criteria. It is the most widely used staging system and has been adopted by the Musculoskeletal Tumor SocietyThe system should be reserved for staging mesenchymal lesions rather than nonmesenchymal ones (such as the lesions lymphoma, and leukemia), because the biologic behavior of nonmesenchymal tumors differs from that of mesenchymal lesions. For example, studies have shown that the site of occurrence of Ewing sarcoma is not a significant factor when tumor size is considered.

Grade

  In the Enneking system, bone tumors are graded as follows: G0 - Benign lesionA  G1 - Low-grade malignant lesion  G2 - High-grade malignant lesion 

  Surgical grade generally follows histologic grade; however, a higher surgical grade may be applied if the radiographic features and clinical behavior of a lesion indicate an aggressiveness that is incompatible with its benign histologic features.

Site

  In the Enneking system, the site and local extent of bone tumors are classified as follows: T0 - A benign tumor that is confined within a true capsule and the lesion's  anatomic compartment of origin (ie, a benign intracapsular, intracompartmental lesion) T1- An aggressive benign or malignant tumor that is still confined within its  anatomic compartment (ie, an intracompartmental lesion) T2 - A lesion that has spread beyond its anatomic compartment of origin (ie, an  extracompartmental lesion)

Metastasis

  Metastatic classification in the Enneking system is as follows: M0 - No regional or distant metastasis

   M1 - Regional or distant metastasis

   Staging

  Under the Enneking system, malignant tumors are classified into stages I-III, with further subdivisions into A and B. Grade 1 and grade 2 tumors are stage I and stage II, respectively. T1 and T2 tumors are stage A and stage B, respectively. Tumors with distant metastasis are stage III (see Table 1 below).

  Stage Grade Site Metastasis

  IA G1 T1 M0

  IB G1 T2 M0

  IIA G2 T1 M0

  IIB G2 T2 M0

  III G1 or G2 T1 or T2 M1

Staging of Benign Tumors

  The Enneking staging system divides benign tumors into latent, active, or aggressive tumors (see Table 2 below). Latent tumors are asymptomatic and are usually discovered incidentally. They reach a stage of nongrowth after a period of slow growth. Active tumors are mildly symptomatic and may be discovered if pathologic fracture occurs or if the tumor is associated with mechanical dysfunction. Active tumors usually grow steadily. Aggressive benign lesions grow rapidly and usually are symptomatic and tender on palpation. Table 2. Enneking System for the Surgical Staging of Benign Lesions

  Stage Description Grade Site Metastasis

  1 Latent G0 T0 M0

  2 Active G0 T0 M0

  3 Aggressive G0 T1 or T2 M0 or M1

Limb Salvage Surgery and Staging

  The aims of limb salvage surgery are to cure disease and to preserve limb function for the patient. The aims are usually achieved by using a combination of limb salvage surgery and adjuvant therapy. Limb salvage operations are indicated if the following conditions are satisfied:

  The tumor is situated in the extremities and/or the axial skeleton.  The tumor margins are amenable to surgery.  Only moderate soft-tissue extension is present.

   The neurovascular bundles are intact.

   Metastases are absent or amenable to curative treatment.  The patient is in good general health.  Regarding resection margins, optimal surgical margins are 6 cm of healthy bone around the bone margins and 2 cm of healthy soft tissue around the soft-tissue extent of the tumor. If a malignant tumor is responsive to chemotherapy, smaller resection margins may be acceptable. The Enneking classification correlates the tumor stage with the excision margins as follows:

  Benign tumors Stage 1 tumors - Intracapsular excision (or curettage) is adequate.

   Stage 2 tumors - Extracapsular excision passing through the reactive zone is  needed. Stage 3 tumors - Wide margins of resection are required in stage 3 lesions  (aggressive benign tumors). In areas that are not amenable to wide excision, marginal excision together with adjuvant treatment (eg, radiation therapy) may be acceptable.

  Malignant tumors

  Stage IB - Such tumors may be treated with wide excision, but the choice between  amputation and limb salvage depends on the estimated amount of residual tumor left behind after a limb salvage procedure. Stage II - These tumors are high grade, are usually extracompartmental, and have

   a significant risk for skip metastases. They usually are not amenable to limb salvage operations and require radical amputation or disarticulation in most patients. However, bone tumors responsive to chemotherapy may be treated successfully using wide excision and adjuvant therapy. Stage III - Tumors at this stage are responsive to chemotherapy and may be  treated with aggressive resection. Those that are not responsive to adjuvant therapy should be treated with palliative resection.

Radiograph

  Radiography is the initial imaging modality in the evaluation of bone tumors. Some benign lesions have characteristic radiographic features that make biopsy unnecessary. Examples include fibrous cortical defects, bone islands, simple bone cysts, bone infarcts, and typical variants, such as pseudocysts of the humerus and calcaneus. (See the images below.)

  Frontal radiograph in a 9-year-old with trauma to the left knee shows a well-defined, cortically-based lesion with sclerotic margins, situated on the lateral aspect of the left upper tibial metaphysis. The lesion has the typical appearance of a fibrous cortical defect. Enneking stage 0. rontal radiograph in a 10-year- old boy with pain of the left upper limb shows a well-defined, loculated, centrally located lesion in the left humeral metaphysis. Overlying cortical thinning is noted. The lesion has the typical appearance of a unicameral bone cyst. Enneking stage II. rontal radiograph in a 16-year-old girl with pain in the right upper limb shows a metaphyseal lesion with ill-defined, permeative destruction. Cortical erosion and a Codman triangle are seen (arrow). These are the radiographic features of an aggressive lesion that was Radiographic features can also help in distinguishing malignant from benign bone lesions in many patientsLodwick and colleagues established a radiographic grading system based on the analysis of the radiographic features of a bony lesi

  

   Group 2 - Lesions with a high likelihood of being benign but that should be

  rontal radiograph in an 11-year-old girl with back pain shows an ill-defined, lytic lesion in the right iliac bone, just above the acetabulum (arrowheads). The lesion was proven to be a Ewing sarcoma. The Enneking staging system is not used for nonmesenchymal lesions such as Ewing sarcoma.

  In the staging of bone tumors, computed tomography (CT) scanning has a role in the detailed evaluation of local disease and in assessing the lungs for pulmonary metastases. In evaluating local disease, CT scanning complements radiography because it can be used to assess disease in areas that are not easily visualized with radiography, such as the spine and pelvis. In addition, CT scanning is better for use in determining the type of cortical destruction that has occurred and in assessing whether matrix mineralization is present. CT scanning is also helpful in determining the internal contents of some lesions. (See the images below.)

  on which a biopsy should be performed to confirm the diagnosis and histologic grade

   Group 4 - Aggressive-appearing lesions that should be considered malignant but

  behavior or a risk of pathologic fracture

  

 Group 3 - Benign lesions that require surgical resection because of aggressive

  confirmed as benign by means of clinical or radiographic follow-up examination

  or treatment

  he important radiographic signs for grading bone tumors is listed as follows, in order of priority:

    Group 1 - Radiographically benign lesions that do not require further investigation

   Grade 3 - High-grade malignant lesions with invasive, permeative, and destructive features Another grading system divides bone lesions into 4 groups, each with individual management algorithms

   Grade 2 - Low-grade malignant lesions with invasive features; applies particularly to lesions demonstrating total penetration of the cortex

   Grade 1A, 1B, and 1C - Benign lesions with edge characteristics ranging from well defined to poorly defined

   Absence or presence of the expanded cortical shell, as well as its extent The grading system developed by Lodwick and coauthors groups lesions into 3 grades.

   Penetration of the cortex by the lesion  Absence or presence of a sclerotic rim

  interface zone

  

 Pattern of destruction - Geographic or not geographic, appearance of marginal

CT Scan

  puted tomography (CT) scan demonstrates the characteristics of a lytic lesion, such as destruction of the thin, overlying cortex (arrow) of the right iliac bone. puted tomography (CT) scan of the lungs shows multiple lung metastases (white arrows) and bilateral pleural effusions (black arrows) in a patient with osteosarcoma of the humerus. Enneking stage III. Although magnetic resonance imaging (MRI) is generally accepted to be superior to CT scanning in the evaluation of local tumor spread, Panicek and colleagues have shown that CT scanning and MRI are equally accurate in the staging of local disease in bone tumors. CT scans have been shown to be more accurate than chest radiographs in evaluating the lungs for the presence of metastases. However, CT scans may produce false-positive results when small lung nodules are detected. Follow-up CT scans are useful in monitoring the nodules. Apostolova et al studied the use of single-photon emission computed tomography (SPECT), compared with planar bone scanning, in 271 patients with tumors of the spine and pelvis, and they suggested that SPECT be used in patients with equivocal findings on planar imaging. Retrospective image interpretation was performed independently for planar and SPECT scans. SPECT changed definite staging on planar images in fewer than 4% of patients, but in patients with planar equivocal staging, SPECT provided a definite diagnosis in more than 80%

MRI

  MRI has several advantages compared with other imaging modalities in visualizing and staging bone tumors. In particular, accurate depiction of the soft tissues allows sensitive detection of soft-tissue extension of and medullary involvement by a tumor. MRI can be performed in several orthogonal planes. The absence of ionizing radiation and beam- hardening artifacts are advantages of MRI compared with CT scanning. MRI is the modality of choice for the imaging and staging of bone tumors.

  Technical considerations for MRI Obtain magnetic resonance images before performing a biopsy.

   Position the patient comfortably to minimize motion artifacts.  Sedation is often required in children.  Place a vitamin E or cod liver oil capsule over the site of interest.  Use the appropriate coils.

   Perform the imaging in at least 2 planes.

   Sequences

  Perform conventional T1-weighted and T2-weighted, spin-echo sequences

   because they provide reproducible images. Typically, pathology appears as areas of low signal intensity on T1-weighted images and as areas of high signal

  Fast spin-echo sequences with fat suppression also are popular imaging  sequences, and they are used in many centers because of the time-saving advantages (see the image below). steosarcoma of the right humerus. Fast spin-echo, T2-weighted, coronal magnetic resonance image shows a large, metaphyseal-based lesion of mixed signal intensity with a large, soft- tissue component (arrows). Enneking stage IIB. Short T1 inversion recovery (STIR) sequences provide fat-suppressed images  with T1- and T2-additive effects (see the image below). STIR sequences are particularly useful for the detection of small lesions and bone marrow abnormalities hort T1 inversion recovery (STIR), coronal magnetic resonance image shows the lesion's extent and a large, soft-tissue component. Enneking stage IIB.

MRI contrast agents

  The intravenous administration of gadolinium diethylenetriamine penta-acetic acid (Gd- DTPA) increases the signal intensity on T1-weighted images by reducing the T1 relaxation time (see the images below). This feature is useful in distinguishing necrosis from an active tumor and in differentiating cystic lesions from solid lesions. Although some authors have indicated that MRI contrast agents do not improve tumor detection or staging accuracy, most authors have found that the administration of MRI contrast agents is useful in making difficult diagnoses.

  1-weighted, fat-saturated, axial magnetic resonance image demonstrates the lesion and its soft-tissue component (arrowheads). Enneking stage IIB. 1-weighted, fat-saturated, axial magnetic resonance image acquired after the intravenous administration of gadolinium diethylenetriamine penta-acetic acid shows marked enhancement and increased signal intensity in the lesion and its soft-tissue component (arrowheads). Enneking stage IIB.

  Gadolinium-based contrast agents have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography (MRA) scans. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness.

Role of MRI in diagnosis

  In many cases, MRI cannot provide a histologic diagnosis of soft-tissue lesionsHowever, some lesions have appearances that are usually characteristic enough for a histologic diagnosis based on the MRI findings. Examples of such lesions include lipomas, superficial and skeletal muscle hemangiomas, benign neural tumors, periarticular cysts, hematomas, and pigmented villonodular synovitis. The most common soft-tissue lesions diagnosed with MRI are lipomas. They appear well circumscribed, homogeneous, and isointense relative to subcutaneous fat on images obtained with all pulse sequences. Thin, low-intensity septa also are sometimes seen in lipomas.

  Some general guidelines regarding the relationship between MRI signals and histologic tissue types can be made, as follows: Tumor tissue is usually low in signal intensity on T1-weighted images and high in

   signal intensity on T2-weighted images. The mineralized matrix is seen as areas of low signal intensity on T1-weighted

   and T2-weighted images. Areas of hemorrhage are seen as areas of high signal intensity on T1-weighted

   and T2-weighted images. The measurement of T1 and T2 relaxation times are useful in determining the

   histologic features. The imaging criteria that are used in differentiating benign from malignant lesions on radiographs and CT scans have been applied to MRITypically, benign lesions are well defined and sharply demarcated from the surrounding healthy tissue. Malignant lesions are typically more extensive and involve surrounding tissue to a greater extent than do benign lesions. However, MRI signal intensity alone is not reliable in distinguishing between benign and malignant tumors.

  Erlemann and colleagues reported that dynamic imaging after contrast enhancement is approximately 80% accurate in differentiating benign tumors from malignant ones. MRI

   reported that the presence of abnormal marrow or soft tissue around a chondroid tumor is suggestive of chondrosarcoma, especially if bony destruction or aggressive radiographic features are lackingOther benign lesions with characteristic MRI findings include osteochondromas, chondromas, aneurysmal bone cysts, and nonossifying fibromas

Role of MRI in staging

  MRI is the modality of choice in assessing local spread of tumor (Enneking sites T1 and T2). MRI can help in accurately detecting tumor involvement of neurovascular structures, muscle compartments, growth plates, and joints.

  MRI is accurate in determining involvement of the neurovascular bundle (see the image below). MRA may provide additional information regarding neurovascular bundle involvement. MRA can help in assessing peripheral vascular branches and tumor neovascularity. By demonstrating treatment-induced changes in tumor neovascularity, MRI may also help in assessing a tumor's response to treatment.

  ast spin-echo, T1-weighted, axial magnetic resonance image obtained with fat saturation and the administration of gadolinium diethylenetriamine penta-acetic acid, in a 13-year-old boy with osteosarcoma of the left distal femur. The image shows enhancing tumor tissue that extends circumferentially into the surrounding soft tissues. The distal femoral vessels are almost involved (arrowheads). Enneking stage IIB. Although MRI usually accurately depicts the intramedullary spread and soft-tissue extension of a tumor (see the image below), differentiating tumor edema from true tumor spread may occasionally be difficult. Typically, edema is seen as an ill-defined, homogeneous, hyperintense area with a featherlike appearance. Edema tends to follow the tissue planes; it has no mass effect, and unlike the distinct pseudocapsule of tumor tissue, it possesses a fading margin. The administration of Gd-DTPA also aids in the distinction of tumor tissue from tumor edema, because tumor tissue enhances and edema does not. Intramedullary spread and soft-tissue extension of a tumor are more accurately assessed with MRI than with CT scanning.

  Fast spin-echo, T2-weighted, coronal magnetic resonance image with fat saturation demonstrates the presence of a tumor within the medullary cavity (small arrow) and extending to the midshaft of the femur (large arrow). Soft-tissue tumor extension is shown (arrowheads). Enneking stage IIB.

  The accuracy of MRI in the evaluation of joint involvement is controversial (see the image below). Some authors have found MRI to be more accurate than CT scanning in demonstrating joint involvement, although Bloem and colleagues found that CT scanning and MRI provided similar results in their study. Enhancement of joint synovium after Gd- DTPA administration may mimic tumor involvement. Joint effusion alone is not diagnostic of tumor involvement. at-saturated, T1-weighted, contrast-enhanced, coronal magnetic resonance image in an 8-year-old boy with osteosarcoma of the right upper humerus shows an enhancing tumor involving the shoulder joint. Enneking stage IIB.

Role of MRI in assessing the response to treatment

  MRI is increasingly used to assess tumor response to preoperative chemotherapy (see the images below). This assessment is achieved by evaluating changes in a tumor's size, margins, signal intensity, and enhancement patterns.

  rechemotherapeutic, T1-weighted, axial magnetic resonance image in a 19-year-old man with B-cell lymphoma of the left humeral head shows a low–signal-intensity tumor involving the left humeral head (H). A soft-tissue mass surrounds the humeral head (arrowheads), with involvement of the glenohumeral joint (arrow). Enneking stage IIB. ostchemotherapeutic, T1-weighted, axial magnetic resonance image shows that the humeral head has regained normal signal intensity (H). Resolution of the soft-tissue mass is almost complete. No glenohumeral joint involvement is present at this time. Enneking stage IIA. After chemotherapy, a poor tumor response with no reduction in tumor size usually indicates a poor histologic response; however, a substantial reduction in tumor size does not necessarily indicate a good prognosis. In most patients with Ewing sarcoma, a marked decrease in tumor size is an expected finding MRI findings of residual soft-tissue components and tumor volume are usually correlated with the histologic response of the tumor to chemotherapy. Tumors that decreased in size by 25% and 75% after chemotherapy have a substantial overlap between good responses and poor responses.

Postchemotherapeutic MRI signal–intensity changes

  MRI patterns are often unpredictable because tumors undergo necrosis, hemorrhage, edema accumulation, granulation-tissue formation, and fibrosis after chemotherapy. {Ref37}Some general indicators of a good response to chemotherapy include the following:

  A circumferential hypointense rim combined with a decrease in size of the soft-  tissue component in patients with Ewing sarcoma Increased homogeneous signal intensity on T2-weighted images in Ewing  sarcoma (indicating tumor replacement by a hypocellular mucomyxoid matrix)

Contrast-enhanced MRI

  The intravenous administration of Gd-DTPA helps in differentiating remnant tumor from nontumorous tissue. Because of its greater vascularization, tumor tissue enhances more than does nontumorous tissue. However, the presence of vascularized granulation tissue, neovascularity in necrotic areas, or reactive hyperemia also may cause Gd-DTPA enhancement on static MRIs, making tumor-free tissue difficult to differentiate from tumor tissue.

  Dynamic, contrast-enhanced magnetic resonance images are better than static images for determining a tumor's response to chemotherapy (see the images below). Images in patients who respond well to chemotherapy show a reduction in enhancement, whereas those of patients who respond poorly show little or no reduction. Images should be acquired by using short time intervals because reactive changes may show contrast enhancement indistinguishable from that of tumor in the later phases of enhancement.

  steosarcoma of the left upper humerus. Contrast- enhanced, dynamic, coronal, color magnetic resonance image shows the degrees of enhancement of the tumor at different regions of interest (1-4). Enneking stage IIB.

  ynamic time-intensity curves show a steep uptake of contrast material in the region of the viable tumor. A nonviable tumor shows a gradual gradient of contrast agent uptake. Parametric first-pass imaging and subtraction MRI have been used to increase the detection of early arterial enhancement of residual viable tumor.

  The use of magnetic resonance spectroscopy with phosphorus-31 in assessing changes in tumor metabolism and in monitoring changes in spectra has been evaluated. There are still limitations to this technique because of the difficulty of obtaining representative spectra in all locations in the tumor, the contamination of tumor spectra with phosphorus in adjacent soft tissues, and the technique's insensitivity to tumor heterogeneity.

  Role of MRI in detecting recurrence

  The differentiation between tumor recurrence and chronic posttherapeutic changes administration and appears hyperintense on T2-weighted images. Chronic, posttherapeutic changes in a nonnodular lesion have low to intermediate signal intensity on T1-weighted images and lack high signal intensity on T2-weighted images. Static, contrast-enhanced MRI may not always be helpful in distinguishing recurrent tumors from posttherapeutic changes because the latter may also show enhancement after the administration of Gd-DTPA. Dynamic, contrast-enhanced MRI may be beneficial by demonstrating early enhancement in tumor tissue that is not seen in posttherapeutic changes. Fatty marrow may reconvert to hemopoietic marrow in children with osteosarcoma who have been treated with chemotherapy and granulocytic colony-stimulating factor. When such reconversion occurs in a patient, the marrow's appearance on magnetic resonance images may resemble that of a recurrent tumor, although reconverted marrow usually appears bilateral and symmetric. The reconverted marrow's signal intensity is similar to that of skeletal muscle, unlike the signal-intensity characteristics of a recurrent tumor.

  Tumor recurrence may be hard to detect when orthopedic implants are in close proximity to tumor sites. Orthopedic implants may cause susceptibility artifacts, making evaluation of the surrounding tissues difficult. Susceptibility artifacts occur at interfaces of structures with markedly different magnetic susceptibilities. Pure titanium orthopedic implants are nonferromagnetic, whereas some alloys are ferromagnetic. Susceptibility artifacts may be decreased by optimally positioning patients with orthopedic implants, by switching the orientation of the frequency- and phase-encoding gradients, by using the smallest voxel size, and by choosing fast spin-echo sequences. Susceptibility artifacts are more severe in gradient-echo sequences and in sequences with a long echo time.

Radiologic Studies and Intervention Nuclear medicine studies

  99m

  Radionuclide bone scans are commonly obtained by using technetium-99m ( Tc)– labeled diphosphonate to stage bone tumors. Radionuclide bone scanning has a role in detecting metastases, skip lesions, lesion multiplicity, and postoperative tumor recurrence. Bone-forming, metastatic lesions in the lungs (eg, osteosarcoma) are occasionally detected with bone scintigraphy (see the image below).

  isarticulation of the right shoulder was performed in this patient with right humeral osteosarcoma. A radionuclide bone scan obtained 5 months after surgery shows abnormal focal areas of increased tracer uptake in the right scapula, left upper humerus, and right distal femur (arrows). These uptake areas correspond to bony metastases. Abnormal areas of increased tracer uptake are seen in the lungs, corresponding to pulmonary metastases (arrowheads). Enneking stage III.

  Areas showing increased tracer uptake in the skeleton should be evaluated by using radiography. Further evaluation with CT scanning or MRI may be necessary if plain radiographic findings are negative. Biopsy may be necessary if a positive result might

Ultrasonography

  Soft-tissue masses and the soft-tissue components of bony tumors may be visualized by using ultrasonography (US) The histologic diagnosis of the lesions usually cannot be made by using US. The aim of US in the evaluation of musculoskeletal lesions is to confirm the presence of a lesion, to determine if the lesion is cystic or solid, to assess the relationship of the mass to the surrounding structures (eg, neurovascular bundle), to evaluate the vascularity of the mass, and to guide interventional procedures if indicated.

  Although color Doppler ultrasonographic evaluation of the mass is unreliable in determining the histologic diagnosis of the lesion and whether the lesion is benign or malignant, color Doppler US is a useful tool for monitoring the regression of tumor neovascularity induced by therapy in patients with musculoskeletal sarcoma. When the clinical findings suggest the recurrence of a soft-tissue sarcoma, US can be used as the initial imaging technique for evaluation. US can also be used in addition to MRI when susceptibility artifacts secondary to orthopedic hardware (including prostheses) prevent the evaluation of specific areas.

Angiography

  Currently, angiography is used only occasionally to evaluate neurovascular bundle involvement. Its role has largely been replaced by cross-sectional imaging modalities. Angiography still has a postoperative role in decreasing hemorrhage through the embolization of tumor-supplying vessels (see the images below).

  re-embolization, bilateral iliac angiogram in a 51-year- old man with sacral chordoma shows tumor hypervascularity (arrows). Image courtesy of Austin MM Htoo, FRCP, FRCR. ostembolization angiogram shows a reduction of tumor vascularity. The embolization was performed using Gelfoam and coils. Image courtesy of Austin MM Htoo, FRCP, FRCR.

Positron emission tomography scanning

  Positron emission tomography (PET) scanning was developed in the 1960s and has increasingly been used in some centers for detecting and staging malignancy. PET scanning can be used to image tumor metabolism because of the detection of photons emitted from tissue after the intravenous injection of a pharmaceutical, such as 2- [fluorine 18]-fluoro-2-deoxy-D-glucose (FDG). These photons are detected by the PET scanner and reconstructed into a 3-dimensional image. Tumor metabolism is higher than that of normal tissue and shows higher FDG uptake. In bone tumors, the degree of FDG uptake is related to the histologic grade of the nonossifying fibromas, fibrous dysplasia, giant cell tumors, eosinophilic granulomas, and aneurysmal bone cysts. According to Bischoff et al, combined FDG-PET-CT reliably differentiates soft tissue and bone tumors from benign lesions. The authors performed a retrospective study to determine whether integrated FDG-PET and CT (FDG-PET-CT) is more accurate than the 2 modalities interpreted separately. Sensitivity, specificity, and accuracy for CT alone was 81%, 84%, and 83%. Sensitivity, specificity, and accuracy for PET was 71%, 82%, and 76%. Sensitivity, specificity, and accuracy for FDG-PET-CT was 80%, 83%, and 86%. PET has been shown to have a sensitivity similar to that of serial CT scanning and MRI for detecting lesions and for distinguishing postsurgical scarring from recurrent tumors. However, the specificity of PET is higher than that of serial CT scanning or MRI. In evaluating musculoskeletal sarcomas, when it comes to detecting recurrent tumor, FDG-PET scanning has higher sensitivity and specificity, as well as a greater positive and negative predictive value, than does iodine-131-meta-iodobenzylguanidine (MIBG) scanning. In summary, PET scanning appears to be better than CT scanning and MRI in depicting residual or recurrent tumor after treatment. The main disadvantage of PET scanning is the high cost of the equipment, which limits the modality's availability.

Radiologic intervention

  Image-guided biopsy is less expensive and safer than open biopsy. The biopsy site should be located where the needle tract will be excised in future surgery, because of possible tumor seeding along the needle tract. Fluoroscopy with C-arm guidance, CT scanning, and MRI can be used to locate the most appropriate biopsy site. The primary advantage to fluoroscopy is its ability to create dynamic images. CT-guided biopsy is usually employed if the lesion is located in a complicated part of the anatomy, such as the upper thoracic spine or pelvis (see the image below).

  opsy of a vertebral body tumor. A 17-gauge bone- cutting needle is inserted through the left T11 pedicle (arrow). For aspiration cytology, a fine-gauge needle is used. For a lesion that predominantly consists of soft-tissue components, a cutting needle is usually chosen. For bone tumors, a combined trephine and cutting needle is utilized. The needle tract should pass through the bony and soft-tissue components of the tumor, allowing for complete histologic examination. Hemorrhage, infection, and trauma to surrounding tissues are complications of biopsy.

Conclusion

  Imaging plays a crucial role in staging bone tumors. Radiography, occasionally with the aid of CT scanning, is required for the detection and diagnosis of bone tumors. CT scanning and bone scintigraphy are useful in depicting pulmonary metastases and the multiplicity of lesions, respectively. MRI is the modality of choice in staging bone tumors

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Musculoskeletal Disordermsds Musculoskeletal Disorders Musculoskeletal Complaints Musculoskeletal Disorder Keluhan Musculoskeletal Benign Prostate Tumor Benign Prostate Hyperplasia Fourier Transform Infrared Ftir Spectroscopy Of Biological Tissues Benign Prostatic Hyperplasia
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