RESUMO
Signet-ring cells are morphologically defined by the presence of a large intracytoplasmic vacuole that compresses and displaces the nucleus to the periphery. In most cases, these cells are associated with adenocarcinomas of various locations, and with non-epithelial neoplasms. To date, less than 20 cases of squamous cell carcinoma with signet-ring morphology have been described, mainly located on the skin. We present the case of a 73-year-old male with pleural effusion and a left lower lobe mass. The cytological study of the pleural effusion allowed the diagnosis of metastasis of squamous cell carcinoma, signet-ring cell variant. The treatment of lung cancer in advanced stages requires a precise diagnosis that allows the best therapy to be offered to the patient, depending on the clinical stage and the positivity of the biomarkers, among others. Our patient died 18 months after the initial diagnosis.