PMC3843908_01
a A reddish-brown dome-shaped hyperkeratotic nodule on the left lower leg. b The lesion showed a whitish scaly area, pinkish-white structureless areas, a few milia-like cysts, dotted and glomerular vessels, light brown globules, and dotted hemorrhages on dermoscopy.
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F1
Physical examination revealed a reddish-brown dome-shaped hyperkeratotic nodule of 11 x 10 mm with a sharply demarcated, symmetrical border (fig. 1a). Dermoscopic examination demonstrated prominent whitish scaly areas of ring-like appearance, pinkish-white structureless areas, a few milia-like cysts, dotted and glomerular vessels, light brown globules, and dotted hemorrhages (fig. 1b).
a Panoramic view revealed a well-circumscribed symmetric lesion with hyperkeratosis, acanthosis, and pseudohorn cysts. b The lesion was composed of spindle-shaped and epithelioid melanocytes with large cytoplasm arranged in confluent nests with peripheral clefts. c There was stromal fibrosis surrounding the nests. d At the papillary layer, proliferation of capillary could be found. HE.
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F2
Hyperkeratosis, acanthosis, and pseudohorn cysts were observed (fig. 2a). There were confluent nests with peripheral clefts composed of spindle-shaped and epithelioid melanocytes with large cytoplasm at the dermal-epidermal junction and in the papillary dermis (fig. 2b). There was stromal fibrosis surrounding the nests (fig. 2c). Moderate proliferation of capillaries in the papillary dermis was observed (fig. 2d).
a Melan-A staining showed weaker findings in the deeply situated cells than in the superficial cells. b Nests were partly ascending into the stratum corneum. Melan-A staining.
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F3
Melan-A was weaker in the deeply situated cells than in the superficial ones (fig. 3a), and nests ascending up to the stratum corneum appeared as transepidermal elimination (fig. 3b).