Abstract
Leser–Trélat sign is a cutaneous manifestation that presents with rapid onset of multiple seborrheic keratoses on the trunk and extremities. In the majority of cases, seborrheic keratoses increase in number within short periods (usually within 6 months). Seborrheic keratoses are commonly seen in elderly people; however, Leser–Trélat sign is important because it may be a clue to the discovery of occult internal malignancies. Adenocarcinomas involving the stomach, intestine and breast are commonly associated with Leser–Trélat sign, however, hematological malignancies have also been detected. Several reports have shown that Leser–Trélat sign is associated with benign neoplasms. Although the etiology of Leser–Trélat sign is largely unknown, several speculations have been proposed. EGF and TGF-α are derived from the original tumor cells, while EGF-receptor (EGF-R) is expressed on the epidermis. This suggests that the development of seborrheic keratoses may be accelerated via EGF-R-mediated signaling pathways. Other paraneoplastic signs showing epidermal proliferation include acanthosis nigricans, acquired ichthyosis and Bazex syndrome. The collision of these paraneoplastic signs and Leser–Trélat sign is sometimes reported. These findings suggest that tumor-derived factors exert some effects on keratinocytes. Rarely, seborrheic keratoses regress either spontaneously or possibly via apoptotic process, however, in the majority of cases, the condition is stable in number, even after internal cancers are surgically removed. To date, there is still little evidence of seborrheic keratoses alterations at the clinical and/or molecular levels. In this review, current findings on the possible pathomechanisms of Leser–Trélat sign are discussed.
Financial & competing interests disclosure
The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.
No writing assistance was utilized in the production of this manuscript.
Key issues
• Leser–Trélat sign is associated with, not only malignancies, but also benign tumors, immunosuppressive conditions and even with healthy individuals.
• Leser–Trélat sign can be seen in young patients.
• It is speculated that growth hormones or cytokines derived from internal malignant tumors contribute to the induction of eruptive seborrheic keratosis; however, its evidence is still insufficient.
• Further studies are necessary to clarify the cellular mechanisms in the fading lesions of seborrheic keratosis.