Exfoliative cytology of multiple endobronchial granular cell tumor.

A multicentric endobronchial granular cell tumor (GCT) in a 50-year-old man was diagnosed by the cytologic study of bronchial lavage specimens. The paraffin-embedded sections contained small clusters of medium-sized round tumor cells that had eccentric nuclei without nucleoli and eosinophilic finely granulated cytoplasm, which was positive with the periodic acid-Schiff stain. These cells were distinguishable from the macrophages and bronchial and squamous cells also found in the specimens. The excised tumors histologically mimicked a squamous cell carcinoma. Since 10% of all GCTs occur in the lung, where a multiple presentation can especially mimic a metastatic malignant process, it is important that the possibility of a granular cell tumor be considered in the screening of exfoliative cytologic specimens from the lung.