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Molluscum Contagiosum

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MOLLUSCUM CONTAGIOSUM         Lidya Imelda Laksmi     DEPARTMENT ANATOMIC PATHOLOGY MEDICAL FACULTY UNIVERSITAS SUMATERA UTARA  Universitas Sumatera Utara CONTENTS I. INTRODUCTION ……………………………………………………………….. 1 II. POXVIRUS INFECTIONS ……………………………………………………... 2 III. INCIDENCE ……………………………………………………………………... 2 IV. PATHOGENESIS ………………………………………………………………. 3 V. CLINICAL MANIFESTATIONS ……………………………………………….. 3 VI. PATHOLOGY …………………………………………………………………... 4 Microscopic ……………………………………………………………………. 4 VII. DIFFERENTIAL DIAGNOSE ………………………………………………….. 5 VIII. REFERENCES …………………………………………………………………. 7 Universitas Sumatera Utara MOLLUSCUM CONTAGIOSUM Lidya Imelda Laksmi Department Anatomic Pathology Medical Faculty Universitas Sumatera Utara Introduction Molluscum contagiosum is a common non-cancerous skin growth caused by a viral infection in the top layers of the skin. They are similar to warts but are caused by a different virus 1. Molluscum contagiosum, a cutaneous and mucosal eruption caused by a Molluscipox virus (poxvirus 2 1,3,4 ), was first described and later assigned its name by Bateman in the beginning of the nineteenth century. In 1841 Henderson and Paterson described the intracytoplasmic inclusion bodies now known as molluscum or Henderson-Paterson bodies. In the early twentieth century, Juliusberg, Wile, and Kingery were able to extract filterable virus from lesions and show transmissibility. Goodpasture later described the similarities of molluscum and vaccinia. Though generally thought to infect only humans, but there are a few isolated reports of Molluscum contagiosum occuring in chickens, sparrows, pigeons, chimpanzees, kangaroos, a dog, and a horse. The infection is found worldwide and has higher incidence in children, sexually active adults, and those who are immunodeficient 1,2,5. Poxviruses are the largest animal viruses and are the only viruses that are visible by light microscopy. Three groups affect humans: orthopoxviruses such as variola and vaccinia, which are ovoid and 300 x 250 nm in diameter; parapoxviruses such as those which cause orf and milker’s nodule, which are cylindrical and 260 x 160 nm in diameter; and the molluscum contagiosum virus, which has an oval, bullet shape and is 275 x 200 nm in diameter 3,4,5,6 . Humans also may be affected by tanapox, which is somewhat similar to the parapoxviruses. These are complex DNA viruses that replicate in the cytoplasm and are adapted to proliferation in keratinocytes. Spread is primarily by direct contact with infectious material from an infected individual or animal or via fomites, although variola is spread via aerosolized droplets 4. Universitas Sumatera Utara POXVIRUS INFECTIONS Orthopoxviruses Variola Vaccinia Cowpox Parapoxviruses Orf Milker’s nodule Tanapox Virus of molluscum contagiosum Incidence Molluscum contagiosum virus (MCV) can be found worldwide with a higher distribution in the tropical areas. The disease is more prevalent in children with the lesions involving the face, trunk, and extremities. In adults the lesions are most often found near the genital region. The disease is endemic with a higher incidence within institutions and communities where overcrowding, poor hygiene, and poverty potentiate its spread. Over the last 30 years its incidence has been increasing, mainly as a sexually transmitted disease, and it is particularly rampant as a result of concurrent human immunodeficiency virus (HIV) infection. The worldwide incidence is estimated to be between 2% and 8%. Less then 5% of the children in the United States are believed to be infected. Between 5% and 20% of patients with HIV have symptomatic MCV. There are four main subtypes of molluscum contagiosum: MCV I, MCV II, MCV III, and MCV IV. All subtypes cause similar clinical lesions in genital and nongenital regions. Studies show MCV I to be more prevalent (75%–90%) than MCV II, MCV III, and MCV IV, except in immunocompromised individuals. There are, however, regional variations in the predominance of a given subtype and differences between individual subtypes in different countries 2. Universitas Sumatera Utara Pathogenesis This disease is transmitted primarily through direct skin contact with an infected individual. Fomites have been suggested as another source of infection, with molluscum contagiosum reportedly acquired from bath towels, tattoo instruments, and in beauty parlors and Turkish baths. The average incubation time is between 2 and 7 weeks with a range extending out to 6 months. Infection with the virus causes hyperplasia and hypertrophy of the epidermis. Free virus cores have been found in all layers of the epidermis. So-called viral factories are located in the malpighian and granular cell layers. The molluscum bodies contain large numbers of maturing virions. These are contained intracellularly in a collagen-lipid-rich saclike structure that is thought to deter immunological recognition by the host. Rupture and discharge of the infectious virus-packed cells occur in the center of the lesion. MCV induces a benign tumor instead of the usual necrotic pox lesion associated with other poxviruses 2. Reed and Parkinson studied the histogenesis of molluscum contagiosum and concluded that the lesion arises on the basis of follicular neogenesis. They found areas of hair bulb differentiation at the periphery, occasionally associated with areas of sebaceous gland differentiation. However, the disease can also appear in places where there are no hair follicles, such as the palms, indicating that the epidermis itself may be affected 7,8. Clinical manifestations MCV produces a papular eruption of multiple umbilicated lesions. The individual lesions are discrete, smooth, and dome shaped. They are generally skin colored with an opalescent character 1,2,3 often pruritic 3. The central depression or umbilication contains a white, waxy curdlike core. The size of the papule is variable, depending upon the stage of development, usually averaging 2-6 mm 2. Rarely, “giant” forms occur measuring up to 2 cm in diameter 3. In people with disease of the immune system, the molluscum may be very large in size (papules may exceed 1 cm 2) and may involve the face 1. The papules may become inflamed spontaneously or after trauma and present atypically in size, shape, and color. The lesions are often grouped in small areas but may also become widely disseminated 2,3. Any cutaneous surface may be involved, but favored sites include the axillae, the antecubital and popliteal fossae, and the crural folds. Rarely, MCV lesions occur in the mouth or conjunctivae. Autoinoculation is common. Children usually acquire molluscum nonsexually at Universitas Sumatera Utara both genital and nongenital areas. MCV in adults affects the groin, genital area, thighs, and lower abdomen and is often acquired sexually. Around 10% of cases develop an eczematous dermatitis around the lesions, but this disappears as the infection resolves. Patients with atopic dermatitis can have a disseminated eruption. Eruption in immunocompromised individuals are very resistant to treatment 2,3. A B A. The typical molluscum contagiosum lesion is a small firm umbilicated papule with a smooth, waxy, or pearly surface. B. Molluscum Contagiosum in a patient with the acquired immunodeficiency syndrome PATHOLOGY Microscopic Smears of these lesions are easily obtained by squeezing the lesion and expelling its core on a slide that may be immediately examined after methylene blue staining 9, Giemsa 2,3 , Gram, 2 Wright, Papanicolaou . The smears show a large number of “molluscum bodies”, which are squamous cells filled with masses of viral particles, displacing the nucleus to the periphery 9,10. The microscopic histopathology examination, lesions show cuplike verrucous epidermal hyperplasia. The molluscum contagiosum virus initially enters basal keratinocytes and is accompanied by an increase in cell turnover leading to epidermal proliferation. The basal layer remains intact, whereas cell at the core of the lesion become enlarged as a consequence of the accumulation of masses of viral material and appear as large, purplish red bodies (molluscum bodies) that are up to 25 µm in diameter. There is a distinct lobulated character to the proliferation with formation of a central crater that corresponds to the central umbilication observed clinically. Lesions typically have an exo-/endophytic appearance. Inflammatory changes in the dermis are usually minimal but may be pronounced when lesions rupture and Universitas Sumatera Utara discharge their contents. 3,4,5,6,7. Hematoxylin and Eosin. A biopsy revealed lobules of keratinocytes containing large eosinophilic intracytoplasmic inclusion bodies (Henderson-Patterson, or molluscum bodies). Differential Diagnose Each of the inflammatory poxviral illnesses must be distinguished from the others by clinical setting, number of lesions, histologic findings, and electron microscopy. The acute inflammatory poxviral infections all have similar histologic features and usually exhibit prominent spongiosis, ballooning degeneration, dermal edema, and acute inflammation. Individual lesions demonstrate changes that are distinct and permit differentiation in many cases. In vaccinia and cowpox, the basal layer of the epidermis contains large, eosinophilic cytoplasmic inclusions. There is necrosis of the epithelium with spongiosis, pallor of keratinocytes, and a dense infiltrate consisting mostly of neutrophils, lymphocytes, and some eosinophils. There are also extravased erytrocytes in the dermis with prominent papillary dermal edema 4. Orf demonstrates marked inter and intracellular edema, vacuolization, and ballooning degeneration. A dense infiltrate is seen in the dermis that has a characteristic architecture, consisting mainly of histiocytes and macrophages centrally with lymphocytes and plasma cells at the periphery. Characteristcally, there are very few neutrophils. There is also prominent vascularity with increased number of small blood vessels, many of which show swelling and Universitas Sumatera Utara proliferation of endothelial cells. Ultrastructural studies show viral particles within the cytoplasm of degenerating epidermal cells 4. Milker’s nodule is characterized by multilocular vesicle formation in the epidermis that is strikingly acanthotic. There is characteristically less ballooning degeneration than in orf. There is often marked parakeratosis, and eosinophilic cytoplasmic and intranuclear inclusions are seen commonly. The dermis is edematous, and there is an infiltrate of mononuclear cells that may be granulomatous 4. Universitas Sumatera Utara REFERENCES 1. Molluscum contagiosum, available at: www.djo.harvard.edu/site.php?url=/physicians/oa/674 2. Molluscum contagiosum, available at: sexualhealthcare.net/sexually- transmitteddiseases-molluscumcontagiosum 3. Murphy GF, Sellheyer Klaus, Mihm MC. The Skin. In: Robbins and Cotran Pathologic Basis of Disease. 7th edition. Philadelphia: Elsevier Saunders. 2005; 1266-7. 4. Wetherington RW, Khan ZM, Cockerell CJ. Viral Infections. Barnhill RL, editor. In: Textbook of Dermatopathology. Second edition. McGraw-Hill. 2004; 531-3 5. Andrews GC. Some Virus and Rickettsial Diseases. In: Diseases of the Skin For Practitioners and Students. Fourth edition. Philadelphia and London: W.B.Saunders Company. 1961; 482-5 6. Robboy SJ, Duggan MA, Kurman RJ. The Female Reproductive System. In: Rubin E, Farber JL, editors. Pathology. 3rd edition. Philadelphia: Lippincott Williams & Wilkins. 968. 7. Rosai Juan. Skin. In: Ackerman’s Surgical Pathology. Volume 1. 8th edition. Mosby. 1989; 67. 8. Molluscum contagiosum, available at: www.forces-of-nature.net/sitemap.php?cid=5 9. Koss LG, Melamed MR. The Skin. In: Koss’ Diagnostic Cytologic and Its Histopathologic Bases. Volume II. 5th Edition. Philadelphia: Lippincott Williams & Wilkins. 2006; 1288. 10. Koss LG, Melamed MR. Diseases of the Vagina, Vulva, Perineum, and anus. In: Koss’ Diagnostic Cytologic and Its Histopathologic Bases. Volume I. 5th Edition. Philadelphia: Lippincott Williams & Wilkins. 2006; 478.     Universitas Sumatera Utara
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