Verruciform xanthoma-like phenomenon in seborrheic keratosis

Verruciform xanthoma is xanthomatous dermal infiltrate in a proliferating epidermal lesion and is an uncommon phenomenon. It has been reported in various neoplastic or inflammatory conditions. We report a 72-year-old man who had an asymptomatic 1-cm black nodule on his abdomen. Histopathology showed a typical acanthotic type of seborrheic keratosis characterized by basaloid keratinocyte proliferation and pseudohorn cysts. Many aggregated xanthomatized cells were seen in dermal papillae within the acanthotic epithelium. Papillomatosis, parakeratosis, and neutrophil infiltrates, the histologic features of typical verruciform xanthoma, were not seen. The foamy cells were positive for CD-68 and vimentin and negative for cytokeratin and S-100. No human papillomavirus DNA was found by nested polymerase chain reaction. The blood lipid profile was normal. The presence of verruciform xanthomatous change in seborrheic keratosis provides further evidence that verruciform xanthoma may be a reactive phenomenon occurring in common skin disorders.