Background: Adenoid cystic carcinoma (ACC) is a rare, distinctive salivary gland malignant neoplasm arising infrequently as a primary tumor in the lung. Cytomorphology of lung primary ACC has been rarely reported. To the best of our knowledge, cytopathologic features of the solid type of ACC have not been described as a primary lung tumor.
Case: A case of solid-type primary pulmonary ACC arising in the upper segment of the left mainstem bronchus, suggestively diagnosed cytopathologically by bronchoscope-guided fine needle aspiration (FNA), is presented. Cytopathologic differential diagnoses of ACC with other, more common primary neoplasms of the lung are discussed. FNA smears exhibited a normocellular specimen with several large, densely cellular tissue fragments and individual cells, homogeneous and without prominent atypia. Nuclei were round to oval, with finely granular chromatin. Nucleoli were either absent or inconspicious. The nuclear to cytoplasmic ratio was high. Cytoplasm was minimal; chromatin was bland, with rare chromocenters. There was no nuclear molding. Staining the air-dried smears with May-Grünwald-Giemsa stain revealed metachromatic, magenta material not in spherules or cords but as shapeless structures surrounded by tumor cells.
Conclusion: A preoperative cytopathologic diagnosis of poorly differentiated primary pulmonary ACC can enhance surgical planning and success of tumor resection.