The appearance of acanthosis nigricans may be the first indication of an underlying malignancy.


Clinical features:

(1) sudden onset

(2) rapidly progressive

(3) The patient develops brown, velvety plaques affecting the

(3a) axillae

(3b) groin and genitalia

(3c) neck

(3d) vermilion border of the lips

(3e) umbilicus

(3f) antecubital fossa

(3g) popliteal fossa

(3h) perianal

(3i) mucosal surfaces (unusual in other forms of acanthosis nigricans)

(4) The affected areas show hyperplasia with papillomatosis. Numerous acrochordons may develop

(5) Patients may develop diffuse keratoderma on palms. soles and flexor surfaces of digits.

(6) The lesions regress with effective therapy of the underlying tumor, but may recur with disease progression.

(7) The patient may show other signs of an underlying tumor (weight loss, lymphadenopathy, other).


Underlying tumors may include:

(1) gastric adenocarcinoma (most common site)

(2) other intra-abdominal adenocarcinoma

(3) carcinoid tumors

(4) other endocrine tumors (pheochromocytoma, thyroid)

(5) testicular carcinoma

(6) malignant melanoma

(7) sarcoma

(8) lung cancer

(9) malignant lymphoma

(10) cervical carcinoma

(11) urothelial carcinoma


Histopathologic changes include:

(1) hyperkeratosis

(2) dermal papillomatosis

(3) slight acanthosis


Differential diagnosis:

(1) "benign" acanthosis nigricans (insulin resistance, drugs, hormonal, other)


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