Malignant acanthosis nigricans with occult primary.

A case of generalized malignant acanthosis nigricans of 2 years duration is reported. In spite of the long duration of this cutaneous marker of internal malignancy, the patient was completely asymptomatic and extensive investigations revealed the presence of widespread metastasis of mucin secreting signet cell adenocarcinoma from an unknown primary site. In addition the patient also had acquired hypertrichosis lanuginose and florid cutaneous papillomatosis which are also markers of internal malignancy.