Extensive Acanthosis Nigricans due to rectal carcinoma (4 of 7)

There is no satisfactory dermatological or
cosmetic treatment for acanthosis nigricans, and biopsy of
the skin is neither helpful.
The pigmented areas are reversible only when the tumor is
removed.

Patients with gastric cancer occasionally present with
paraneoplastic syndromes, such as acanthosis nigricans,
membranous glomerulonephritis, microangiographic
hemolytic anemia, arterial and venous thrombi (Trousseau
syndrome), seborrheic dermatitis (Leser–Trélat sign), and
dermatomyositis.

Attention should be focused on the possibility of gastric
adenocarcinoma, although other intraabdominal and pelvic
sites should also be evaluated for possible malignant
disease.