Sign and pseudo-sign of Leser-Trélat: case reports and a review of the literature.

Background: Leser-Trélat is distinguished by a rare paraneoplastic sign that is characterized by the sudden eruption of multiple seborrheic keratoses (SKs), associated with underlying internal malignancies. Similar non-malignancy-associated SK eruptions are referred to as the "pseudo-sign of Leser-Trélat" (PLT).

Objective: Two cases of rapid SK eruptions, one the sign of Leser-Trélat (SLT) and one PLT, are presented, and the literature on SLT and PLT is reviewed.

Methods: A literature review of SLT/PLT was performed by searching the PubMed database for all related English published cases.

Results: We identified 109 cases of SLT and 12 cases of PLT, with a mean patient age of 61.8 years. SK eruptions were observed before (68.3%), after (22.1%), and at the time of (9.6%) malignancy diagnosis. The malignancy most frequently associated with SLT was gastric adenocarcinoma. The most common anatomical location of SK eruptions was the trunk (18.9%). Frequently reported associated signs and symptoms included pruritus (52%) and acanthosis nigricans (38.7%). The most common treatment included surgery (35.8%), chemotherapy (26.9%), and radiation therapy (26.9%). Treatment resulted in clinical improvement (45%), no change (30%), exacerbation (15%), or initial improvement followed by exacerbation of SKs. Patient outcomes included disease stability/ improvement (48.4%), recurrence (9.7%), exacerbation/metastasis/new malignancy (4.8%), and death (37.1%).

Limitations: This was a retrospective study and excluded non-English published cases.

Conclusion: This review updates the existing SLT literature and emphasizes the presence of PLT. Clinicians should be aware that SK eruptions may be early manifestations of an internal malignancy or other pathology. To our knowledge, this is the first review examining both SLT and PLT.