Diagnostic dilemmas in pulmonary cytology.

BACKGROUND: Diagnostic difficulties in pulmonary cytology may be compounded by other medical problems, lack of pertinent information, and the presence of rare tumors. In the current study, the authors describe six cases of lower respiratory tract cytology that presented particular diagnostic challenges or pitfalls. METHODS: Three lung fine-needle aspiration biopsies (FNAB) from three patients, four bronchoalveolar lavages from two patients, and one bronchial washing from one patient, each with histologic confirmation, were reviewed. Cytologic material included direct smears, ThinPrep slides, and cell blocks. Cytologic findings were compared with established cytologic criteria for each final diagnosis. RESULTS: Two cases with Aspergillus infection that demonstrated reactive atypical cells were misinterpreted as squamous cell carcinoma and nonsmall cell carcinoma. Two cases diagnosed as significant atypia and negative, respectively, subsequently were found to show bronchioloalveolar carcinoma (as well as lymphangioleiomyomatosis, which was suspected clinically) and bronchogenic adenocarcinoma, respectively. One lung FNAB from a patient subsequently confirmed to have bronchiolitis obliterans-organizing pneumonia (BOOP) showed reactive pneumocytes that initially were misinterpreted as being suspicious for carcinoid. These reactive pneumocytes were identified histologically in the area of BOOP. The last case was an FNAB of a well differentiated fetal-type adenocarcinoma, an unusual variant of adenocarcinoma that to the authors' knowledge rarely is described in the cytology literature. CONCLUSIONS: Cytomorphologic features of lower respiratory tract pathology combined with appropriate clinical information and diagnostic discretion usually allow accurate diagnoses and should decrease both false-positive and false-negative result rates. Clinical information and radiologic findings may be invaluable, but may not always parallel the cytologic diagnosis.