Leser–Trélat sign associated with lung cancer: a case report and review of the literature

The Leser–Trélat sign is a rare paraneoplastic dermatosis characterized by the abrupt development of multiple seborrheic keratoses within a short period and its association with visceral malignancies. Although gastrointestinal adenocarcinoma is the most commonly reported associated malignancy, lung cancer has increasingly been recognized as a possible underlying tumor. We report a case of a 62-year-old man who developed eruptive seborrheic keratoses on the neck, anterior chest, and back in conjunction with the diagnosis of minimally invasive adenocarcinoma of the right upper lobe. We additionally reviewed eight previously reported cases of lung cancer-associated Leser–Trélat sign and summarized their clinical characteristics. Notably, the paraneoplastic manifestation developed at an exceptionally early tumor stage (T1a(mi)N0Mx), suggesting that the Leser–Trélat sign may occur even in minimally invasive pulmonary adenocarcinoma. Adenocarcinoma was the predominant histological subtype among these cases (6 of 9), further suggesting a potential association between the Leser–Trélat sign and adenocarcinoma. Clinicians should be aware of this cutaneous marker, as its recognition may contribute to the early detection of occult malignancies.