Intranuclear Pseudo-inclusions and Grooves in Fine Needle Aspiration Cytology of Pulmonary Carcinoid Tumor.

Cytologic findings of pulmonary carcinoid have been well described. We report new cytological findings in a case of carcinoid tumor. The patient is a 36-year-old man presenting with hemoptysis of about six months in duration. Chest CT scans showed a well-defined round polypoid lesion measuring 1 × 1 cm within the right upper lobe of the bronchus with hyperinflation of the right upper lobe. Trans-bronchial fine needle aspiration and biopsy were done. Cytologic smears showed isolated and loose clusters of uniform round to spindle shape cells with round centrally located nuclei, fine granular (salt and pepper) chromatin and pale cytoplasm. Intranuclear pseudo-inclusions and grooves were seen in some tumor cells. No mitotic figures or necrosis were evident. A cytological diagnosis of carcinoid tumor was made and histopathologic examination and subsequent immunohistochemical study confirmed the diagnosis. Carcinoid tumor may be reliably diagnosed on fine needle aspiration cytology smears. Intranuclear pseudo-inclusions and grooves may be evident in tumor cells.