Cytology of primary pulmonary mucoepidermoid and adenoid cystic carcinoma. A report of four cases.

BACKGROUND: Mucoepidermoid and adenoid cystic carcinomas are very rare primary pulmonary neoplasms that can be classified under the broader heading of salivary gland-like neoplasms (SGN). Both entities need to be considered in the cytologic differential diagnosis of lung tumors. We reviewed cytologic findings in primary pulmonary neoplasms diagnosed at our institution during the time period 1981 to the present along with outside consultation cases. CASES: Three cases of primary mucoepidermoid carcinoma and one case of primary adenoid cystic carcinoma of the lung were diagnosed based on cytology during the period examined. Patient ages were 16, 25, 47 and 78 years, respectively. The mucoepidermoid cytology specimens were composed of three cell types, mucinous, squamous and intermediate cells, at times associated with extracellular mucin. The adenoid cystic carcinoma consisted of small, uniform cells with dark nuclei, scant cytoplasm and associated, acellular balls of basement membrane material. CONCLUSION: The differential diagnosis for primary pulmonary neoplasms needs to include the rare SGN. Cytologic features of adenoid cystic carcinoma are diagnostic ; those of mucoepidermoid carcinoma are at least suggestive.