A case of Spitz nevus on the right fifth toe, which was difficult to distinguish from malignant melanoma

Abstract

A 29-year-old Japanese woman presented with a brownish papule, 5×8 mm in size, on the lateral aspect of the right fifth toe, which had developed within 3 years. The papule was asymmetrical with hyperkeratosis on the surface, at the center of the lesion. Dermoscopy showed biphasic features consisting of a starburst pattern and a region of regression structures at the distal half of the lesion. Histological examination revealed nests of large spindle cells extending from the epidermis into the dermis. Kamino bodies were observed in the epidermal nests, and the tumor cells exhibited maturation.
The nests in the epidermis of the sweat gland, and the asymmetric features of the epidermal nests made it difficult to distinguish typical Spitz nevus from malignant melanoma and atypical Spitz nevus. However, the lateral aspect of the toe is a specific site, which often appears to be histologically atypical. Therefore, the patient was diagnosed with typical Spitz nevus.[Skin Cancer (Japan) 2016 ; 31 : 26-29]