PMC4881275_01
a Close-up image of an erythematous nodule on the left lumbar region of a 32- year-old woman. b A low-power dermatopathologic view of the lesion, which was comprised exclusively of markedly distended epithelioid melanocytes showing abundant clear cytoplasm. c A high-power view in which the balloon cell component, nuclear pleomorphism and atypia are identified. d The intraepidermal component composed of both nested and single atypical melanocytes with some areas of intraepidermal pagetoid spread. e, f The lymph nodes show near-complete replacement with balloon melanoma cells.
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F1
The lesion of concern was an erythematous and focal eccentric pigmented nodule of 15 mm in diameter (fig. 1a). Histological examinations showed a skin fragment with nearly complete effacement by foamy cells and asymmetry (fig. 1b). Nuclear atypia and mitosis were scarcely displayed (fig. 1c). The intraepidermal component was composed of both nested and single atypical melanocytes with areas of intraepidermal pagetoid spread (fig. 1d). The excised bilateral inguinal lymph nodes showed diffuse replacement of the lymph nodes by foamy cells (fig. 1e, f).
a An immunohistochemical staining of the balloon cell component with Fontana-Masson stain was negative. Immunohistochemical staining of the tumor mass was positive with HMB-45 (b) and S-100 (c). d There was an increased Ki-67 index in the balloon cell component.
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F2
Fontana-Masson staining of the balloon cell component was negative (fig. 2a). S-100 protein (fig. 2c) and negative with cytokeratin. Staining with Ki-67 was positive in almost 44% of the foamy cells (fig. 2d).