Dermatomyositis as the first manifestation of a lung tumor.

Dermatomyositis (DM) is a rare disease characterised by proximal muscle weakness and a typical cutaneous rash. The muscle biopsy shows inflammatory lesions consistent with myositis, being related to an increased risk of cancer, often considered as a paraneoplastic syndrome. The authors present a case of a 63-year-old man, with progressive proximal muscle weakness and cutaneous rash, appearing in two months. The muscle and skin biopsies were consistent with DM. Chest tomography showed a nodular image in the lingular region and bronchy biopsy confirmed the diagnosis of small cell lung carcinoma (SCLC). This clinical case intends to enhance the importance of a thorough diagnostic study in patients with DM, as it is often a paraneoplastic syndrome.