The Pseudo-Sign of Leser-Trélat: A Rare Presentation.

The true sign of Leser-Trélat is a rare cutaneous marker suggestive of an underlying malignancy. Its hallmark finding is the abrupt onset of multiple seborrheic keratoses (SKs) that increase rapidly in number and/or size within weeks to months. When the ominous finding is present, the associated tumor is usually aggressive and portends a poor prognosis. The "pseudo-sign" of Leser-Trélat also presents with the rapid onset of multiple SKs, but without any underlying disease. It is less well-known, and there are only a few reports documenting the phenomenon. This paper reports the case of an 89-year-old male who presented with multiple SKs that rapidly progressed over his scalp, neck, arms, back, trunk, and legs within two to three weeks. A clinical workup revealed elevated pancreatic tumor markers. His cancer antigen (CA) 19-9 levels were 52 U/mL (normal range 0-37 U/mL). Computed tomography (CT) of his abdomen/pelvis without intravenous (IV) and oral contrast showed no evidence of cancer. Bothersome SKs, such as those where his clothes were rubbed against, were destroyed via cryotherapy or shave removal under local anesthesia depending on their size. The patient has remained without any symptoms or findings of an underlying malignancy, confirming that his presentation was consistent with the pseudo-sign of Leser-Trélat. Because it can be concerning when a patient suddenly develops multiple large SKs, recognition of the pseudo-sign is important to determine the appropriate course of action.