Lung Cancer with a Small Cell Carcinoma Component Diagnosed from Pleural Effusion and a Squamous Cell Carcinoma Component Diagnosed from the Tumor

There have been few reports on the accuracy of the diagnosis of small-cell carcinoma based on a cytological examination of malignant pleural effusion, so whether or not such a diagnosis is possible using this approach alone remains unclear. We herein report a 76-year-old Japanese man in whom small-cell carcinoma was diagnosed cytopathologically from pleural effusion and squamous cell carcinoma was diagnosed histopathologically from a transbronchial biopsy. Tumor shrinkage was achieved by treatment with docetaxel, but the efficacy of carboplatin plus etoposide was inadequate. If small-cell carcinoma is detected on the basis of pleural fluid cytopathology alone, it is extremely important to perform a histopathological examination to rule out the possibility of other malignancies.