Verrucous Spitz Nevus in a Japanese Female
A 23-year-old Japanese female presented with a pigmented skin lesion on the left lower leg. It had been noted for 5 months. She had no specific symptoms. Physical examination revealed a reddish-brown dome-shaped hyperkeratotic nodule of 11 × 10 mm with a sharply demarcated, symmetrical border (fig. ). 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. ). The lesion was completely excised under the diagnosis of verruca vulgaris or dermatofibroma.\nHistopathologic study revealed a well-circumscribed symmetric lesion with no lateral extension of individual melanocytic proliferation. Hyperkeratosis, acanthosis, and pseudohorn cysts were observed (fig. ). 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. ). There was stromal fibrosis surrounding the nests (fig. ). Mitotic figures and Kamino bodies were absent. Moderate proliferation of capillaries in the papillary dermis was observed (fig. ). There were perivascular cell infiltration and maturation of nevus cells at the bottom of the lesion. Immunohistochemical staining with melan-A or S-100 was positive for tumor cells, but the staining with HMB-45 was negative. Melan-A was weaker in the deeply situated cells than in the superficial ones (fig. ), and nests ascending up to the stratum corneum appeared as transepidermal elimination (fig. ). We eventually made a diagnosis of verrucous Spitz nevus based on these findings.