High cellular atypia in a pulmonary tumorlet. Report of a case with cytologic findings

BACKGROUND: Pulmonary tumorlets are localized lesions of neuroendocrine cell proliferation, usually found in association with chronic pulmonary inflammation. Since they are mostly incidental histologic or radiologic discoveries, they have received little attention, and there have been no reports on their detailed cytology. We describe for the first time the cytologic features of a pulmonary tumorlet and discuss its differential diagnosis. CASE: An abnormal nodule in the right lung field was discovered on a regular checkup by chest roentgenogram in a 70-year-old, nonsmoking female. Intraoperative aspiration cytology demonstrated cohesive, spindle-shaped cells arranged in fascicles or singly. Since these cells showed nuclear atypia, such as hyperchromasia, a coarsely granular chromatin pattern and nuclear grooving, a nonepithelial malignant lesion was suspected and upper lobectomy performed. The final diagnosis was a pulmonary tumorlet on the basis of histologic examination of the resected material. CONCLUSION: This is the first cytologic report of a pulmonary tumorlet. In this case, differential diagnosis was made of a tumor consisting predominantly of spindle-shaped cells. Although cytologic findings included nuclear atypia, the lesion was not malignant.