Abstract

Verruciform xanthoma is an uncommon, benign lesion which typically develops on the oral mucosa or genitals. We present a case of a verruciform xanthoma with an unusual cystic architecture located on the upper arm of a 69-year-old Caucasian man. The patient had a history of diabetes, end-stage renal disease on dialysis, bilateral lower extremity amputations secondary to complications of diabetes, newly-diagnosed renal cell carcinoma, and morbid obesity. He presented with a several week history of a non-tender, rapidly enlarging, fungating, mobile soft tissue mass with purulent drainage on the left upper arm, measuring 3.5 x 5 cm. This lesion was immediately adjacent to his dialysis fistula. A superficial shave biopsy of the lesion was performed and revealed features of an epidermal inclusion cyst with adjacent scar and overlying features of prurigo nodularis. Given concern about continued growth and proximity to his fistula, two months later the lesion was excised down to fascia by plastic surgery. On complete histopathologic analysis, the tumor was found to be composed of sinus-like spaces with an acanthotic epithelium with elongation of the rete ridges, eosinophilic parakeratosis, and densely infiltrating foamy cells in the papillary dermis. A Brown Hopps stain highlighted the intracorneal gram-positive cocci. No microorganisms were detected with a GMS, PASD, Fite or AFB stain. Thus, the lesion evinced classic characteristics of a verrucous xanthoma with an unexpected cystic architecture. The lesion was entirely excised, with no evidence of recurrence with four months of follow-up. This striking example highlights a rare variant of an already uncommon lesion, expanding the histologic spectrum for the verruciform xanthoma.

Financial Disclosure:
No current or relevant financial relationships exist.