Bullous pemphigoid, malignant acanthosis nigricans, and erysipeloid carcinoma in a woman with gastric adenocarcinoma.

Acanthosis nigricans (AN) is a dermatosis characterized by the presence of hyperpigmented, velvety cutaneous thickening in the flexural areas, posterior neck, and occasionally the extensor surfaces of hand, face, and oral mucosa. AN is commonly associated with insulin resistance, drugs, and rarely internal malignancy (malignant AN). Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by tense blisters involving the skin of mainly elderly patients. The association of BP and malignancy is not well established and the co-existence of BP with AN has not been reported. Here we report a 58-year-old, event-free gastric adenocarcinoma with three types of skin findings with different pathogenesis- BP, malignant AN, and erysipelas-like metastasis.