Acanthosis nigricans can be determined to be benign or malignant by going to the hospital for a pathologic tissue examination. Dermatopathology is the process of taking a small piece of tissue from the affected area and examining it to determine whether the disease is benign or malignant. Acanthosis nigricans is a rare clinical skin disorder characterized by deepening of the skin color or papillary, velvety thickening. Acanthosis nigricans can occur at any age and is associated with cancer in 50% of patients who develop the disease after middle age. The mechanism of the disease is not clear, but it is mainly associated with obesity, tumors, and heredity. If the patient has a deepening of the color of the skin in the armpits, neck, under the breasts, groin or black, gray-brown, it is necessary to go to the dermatology department of the hospital for consultation. It is important to make a clear diagnosis by performing ultrasound, CT, X-ray, and histopathology.