Series Editor: Herbert L. Fred, MD

Prepared by Leslie C. McLemore, Medical Student, and Maulik Shah, MD, PhD, Attending Physician, Saint Louis University School of Medicine, St Louis, Mo

A 49-year-old woman with recently diagnosed invasive ductal carcinoma of the breast had numerous seborrheic keratoses on her chest and back (Figure). The patient said that these skin lesions had developed in a short period of time and had been present for several years.

Points to remember: The relatively abrupt onset of seborrheic keratoses in association with a malignant neoplasm is known as the Sign of Leser-Trélat. The abrupt appearance of these skin lesions in a younger patient is more suggestive of an underlying cancer than in an elderly patient, because cancer and seborrheic keratoses are both common in the older population. In most cases, the tumor originates in the gastrointestinal tract or lung, but a wide variety of malignancies have been implicated. Growth factors produced by the underlying tumor are believed to play a role in the development of the skin lesions. This sign indicates poor prognosis.

Diagnosis: Sign of Leser-Trélat.