The association of acanthosis nigricans and cancer in a great number of cases is well known. This association occurs in 45 per cent of the patients with acanthosis nigricans, according to Mukai;1 in 45.3 per cent, according to Küttner,2 and in 54.5 per cent, according to Moncorps,3 who included cases of definite and probable cancer. The form of acanthosis nigricans which is associated with cancer is called malignant.4
Patients with the benign type of acanthosis nigricans do not suffer from cancer. This negative fact alone, not any difference in the macroscopic or histologic features of the two forms, determines the diagnosis of the benign type. It is true that only in one or two cases has the malignant form been observed in infancy or childhood and that it is the benign type which usually appears in early life, but no sharp division can