Florid cutaneous papillomatosis, malignant acanthosis nigricans, and pulmonary squamous cell carcinoma.

A 72-year-old man had florid cutaneous papillomatosis (FCP), which is an obligatory paraneoplastic syndrome always associated with an internal malignancy. The cancer, which is usually intraabdominal and most often gastric in origin, evolves parallel to the FCP. This patient is the first case of FCP occurring in association with a lung malignancy. An association of FCP with other signs of internal cancer is common, with malignant acanthosis nigricans usually appearing many times with the sign of Leser-Trélat. FCP, malignant acanthosis nigricans, and the sign of Leser-Trélat are part of a continuum, developing by a common or similar pathogenic pathway due to an underlying malignancy producing a factor possibly similar to human epidermal growth factor.