BACKGROUND: Small cell lung carcinoma (SCLC) usually presents as lung or mediastinal lesions. It is very rare for SCLC to present primarily as an isolated pleural effusion with no lung or mediastinal lesions.

CASE REPORT: We report the case of a 77-year-old white male with a 60-pack year history of smoking, chronic obstructive pulmonary disease (stage IV), and asbestos exposure who presented with shortness of breath and left lateral chest pain for 7 days. On physical examination, he was very short of breath, with a prolonged expiratory phase on chest auscultation. Laboratory results were normal except for leukocytosis and chest radiograph revealing left-sided pleural effusion. Computerized tomography (CT) scanning of the chest with IV contrast showed left-sided pleural effusion without any lung or mediastinal lesions. Thoracentesis was performed and fluid was sent for analysis. Repeat CT chest/abdomen/pelvis, done immediately following thoracocentesis, did not show any masses or lymphadenopathy. Fluid analysis, including cytology and immunostain pattern, was consistent with small cell carcinoma.

CONCLUSIONS: Small cell lung cancer presenting as an isolated pleural effusion is extremely rare. It requires close attention to cytology and immunohistochemistry of pleural fluid samples. It also has implications for management and should be managed as limited-stage SCLC.

Keywords: Diagnosis, Differential, Pleural Effusion, Malignant - etiology, Pleural Neoplasms - diagnosis, Small Cell Lung Carcinoma - diagnosis, thoracentesis, Tomography, X-Ray Computed