Metastatic transitional cell carcinoma causing a unilateral pleural effusion: a case report.

Background: Transitional cell carcinoma (TCC) is a common neoplasm, but it is only rarely associated with serous effusions. The cytologic features of metastatic TCC in pleural effusions have been described only in occasional studies. One feature that raises the possibility of metastatic TCC in this setting is the presence of eosinophilic cytoplasmic inclusions (ECIs).

Case: Metastatic TCC was diagnosed in a pleural fluid from a 50-year-old man with a unilateral effusion. Two years previously he had been diagnosed with a poorly differentiated TCC of the urinary bladder (WHO grade 3, stage pT2 at least), and more recently he had also been diagnosed with an omental metastasis. Cytologic examination of the pleural fluid sample revealed numerous pleomorphic malignant cells, many of which were vacuolated. Numerous eosinophilic inclusions were identified within the malignant cells in the liquid based cytology (ThinPrep) preparation. Examination of the omental cake biopsy revealed similar appearances.

Conclusion: ECIs within malignant pleural effusion fluid specimens should, if detected, raise the possibility of metastatic transitional cell carcinoma.