Sputum cytology was performed to rule out primary lung carcinoma in a patient with a cough of recent onset, an infiltrate on chest roentgenography and a history of bladder and prostate carcinoma. The cytology teas interpreted correctly as metastatic transitional cell carcinoma. Review of the cytology by other pathologists without the benefit of the previous history or histologic material resulted in interpretations of reactive/metaplastic tissue. A morphometric comparison of nuclear parameters between the cells in the sputum and the squamous metaplastic cells seen in the sputum of a patient with viral pneumonia from our archives was performed. Evaluation of the current sputum cytology without the benefit of clinical information or additional studies may have led to a false-negative diagnosis.
