Verruciform Acral-Associated (Vacas) Xanthoma: Case Report and Review.

Verrucous xanthoma is a benign histiocytic lesion of macrophage derivation. We describe a woman with a non-mucosal verruciform xanthoma located on her right thumb and review the features of patients with verruciform acral-associated xanthoma. A 69-year-old woman presented with a lesion on her right thumb of eight years duration that had been previously treated with liquid nitrogen cryotherapy without resolution. An initial biopsy was consistent with the surface of a callous. A second biopsy demonstrated a verruciform xanthoma. The patient elected to apply lactic acid 12% twice daily and pare the lesion with a pumice stone once weekly; this resulted in flattening of the xanthoma-associated hyperkeratosis. Acral verruciform xanthoma has, albeit rarely, been described on the hands and feet of individuals. Including the patient in this report, six individuals have been reported with verrucous xanthoma on the hands and 12 individuals have been reported with a verrucous xanthoma on the feet. Verruciform xanthoma most commonly occurs on the oral mucosa. Genital lesions are also a frequent site. Acral-distributed verruciform xanthoma is rare; we propose that a verruciform xanthoma that occurs on acral sites be referred to as a verruciform acral-associated (Vacas) xanthoma.