Cytological analysis of the sputum showed atypical epithelioid cells with vacuolated cytoplasm, large hyperchromatic nuclei, prominent nucleoli, and occasional multinucleated cells in a background of scattered histiocytes and mixed inflammatory cells. The atypical cells were positive for CK7, pan-cytokeratin, CEA, and MOC-31. Tumor cells were negative for TTF-1, p40, CK20, calretinin, CD68, S100, CD45, CD3, CD20, CD30, synaptophysin, S-100, Melan-A, inhibin and WT-1. Histologically, the tumor was diagnosed as invasive pleomorphic carcinoma, as it showed both giant cell and adenocarcinoma components.

Pleomorphic carcinoma (PC) of the lung, a subtype of sarcomatoid carcinoma, is a rare type of non-small cell lung cancer. There have been only a few reports of cytologic analysis in pulmonary PC. Although malignant spindle cells and giant cells can be helpful cytologic features in suspecting PC, definitive  diagnosis requires histologic examination of the complete tumor. This is due to its very poor differentiation, rare incidence, and histological heterogeneity. WHO criteria defines Pleomorphic carcinoma as a poorly differentiated NSCC (squamous cell carcinoma, adenocarcinoma, or undifferentiated NSCC) that contains at least 10% spindle and/or giant cells or a carcinoma consisting only of spindle and giant cells. Carcinomas with pure spindle cell or giant cell carcinoma morphology are diagnosed as spindle cell carcinoma and giant cell carcinoma, respectively. 

It is important to recognize this tumor as a primary lung tumor, and to categorize it as a sarcomatoid carcinoma, in order to facilitate patient-clinician interaction, disease management, and expectations for clinical outcome.