Rare Combined Small-Cell Lung Carcinoma With Lymph Node Metastasis Exclusive to the Small-Cell Component: A Case Report

Combined small-cell lung carcinoma (C-SCLC) is a rare histological subtype characterized by the coexistence of small-cell and non-small-cell components, posing diagnostic and therapeutic challenges due to its heterogeneity and aggressive course. We report the case of a 65-year-old heavy smoker who presented with dyspnea and cough. Imaging revealed a right lower lobe mass, and he underwent pneumonectomy. Pathology showed C-SCLC composed of 70% squamous cell carcinoma and 30% small-cell carcinoma (Ki-67: 60%), with vascular invasion, pleural and bone infiltration, and nodal metastases (pT3N1Mx). Early post-operative recurrence with pleural and osseous metastases was observed, and cisplatin-etoposide chemotherapy was initiated. This case illustrates the poor prognosis of C-SCLC, often undetected on small biopsies due to sampling limitations, and underscores the importance of surgical specimens for accurate diagnosis. Given the absence of standardized treatment protocols, management requires a multidisciplinary and individualized approach.