Malignant Melanoma and Nonepithelial Tumors 351 Malignant Melanoma

Primary malignant melanoma of the penis is a rare disease accounting for less than 1% of all penile cancers.23,96 Preferential location is in the glans (60-80% of all cases), followed by the penile shaft and foreskin.97 Melanomas of the distal penile urethra are even rarer but have been reported and tend to affect the fossa navicularis and infrequently the pendulous urethra or meatus urethralis.23,98,99 Grossly, they present as small, brown or black, often ulcerating, lesions and the clinical aspect is similar to that presented for cutaneous melanomas elsewhere. When affecting the distal urethra, tumors are typically polypoid. Histologically, malignant melanomas show a variegated picture with solid, nested, fusiform or mixed patterns of growth. Tumor cells are polygonal with ample and eosinophilic cytoplasm and marked nuclear atypia in most cases (Fig. 3.19a). Coarse brown intracytoplasmic pigment is usually seen but it may be inconspicuous or even absent (amelanotic melanoma). Presence of clear, vacuolated, rhabdoid or pleomorphic giant cells is not uncommon. Mitoses are abundant and often atypical. As with melanomas in other anatomical sites radial and vertical phases of growth are described. Adverse prognostic factors include presence of ulceration, tumor depth of 3.5 mm or more, and tumor diameter greater than 15 mm.100 Guidelines for the management of penile melanomas have been proposed.93 Distinction between malignant melanoma and other pigmented benign lesions is made following the criteria reported for conventional cutaneous melanocytic lesions. The presence of nuclear pleomorphism, intraepithelial pagetoid spread, and lack of maturation strongly suggest a malignant tumor. Malignant melanoma can also be confused with Paget's disease, especially in its radial phase. When the fusiform pattern of growth predominates, the differential diagnosis should include a sarcomatoid carcinoma and a primary penile sarcoma. Immunohistochemistry for melanocytic markers (S-100, HMB-45 and melan-A) are useful for the differential diagnosis.

Penile Cancer Images

Fig. 3.19 Malignant melanoma and nonepithelial malignant tumors. (a) Malignant melanoma showing pleomorphic neoplastic cells with a solid-fusiform pattern of growth. Melanin pigment is observed in some tumor cells. (b) Kaposi's sarcoma, characterized by a spindle cell neoplastic proliferation with interspersed slit-like vascular spaces. (c) Penile leiomyosarcomas. A pleomorphic spindle cell neoplastic growth is readily observed (Courtesy of Liang Cheng, M.D., Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN). (d) In malignant lymphomas atypical lymphocytes are observed infiltrating penile tissues with a diffuse pattern of growth

Fig. 3.19 Malignant melanoma and nonepithelial malignant tumors. (a) Malignant melanoma showing pleomorphic neoplastic cells with a solid-fusiform pattern of growth. Melanin pigment is observed in some tumor cells. (b) Kaposi's sarcoma, characterized by a spindle cell neoplastic proliferation with interspersed slit-like vascular spaces. (c) Penile leiomyosarcomas. A pleomorphic spindle cell neoplastic growth is readily observed (Courtesy of Liang Cheng, M.D., Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN). (d) In malignant lymphomas atypical lymphocytes are observed infiltrating penile tissues with a diffuse pattern of growth

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Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.

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