Atypical cells in pathology of endobronchial ultrasound-guided transbronchial biopsy of peripheral pulmonary lesions: incidence and clinical significance

Background Atypical cells may occasionally be the only pathologic finding in radial-probe endobronchial ultrasound (EBUS)-guided transbronchial biopsy (TBB) of peripheral pulmonary lesions (PPLs); however, it is uncertain how often we encounter such a situation and what clinical features can be used to identify these ambiguous PPLs, which are more likely to be malignant. Methods From 2009 to 2016, consecutive patients referred for EBUS-guided TBB of PPLs and with pathology reports indicating atypical cells alone were included. Medical records were reviewed to extract patient demographics, clinical characteristics, procedural details and complications. The primary outcome was the final diagnosis of the PPLs on subsequent investigation. Multivariate logistic regression analysis was used to identify independent factors associated with a final malignant diagnosis. Results One hundred sixty-five (7.2%) of 2291 patients had non-diagnostic TBB showing atypical cells. Benign and malignant diagnoses were subsequently obtained in 45 (27%) and 120 (73%) patients, respectively. The leading malignancy was lung adenocarcinoma; of note, a variety of benign lesions revealed cellular atypia on pathology, in particular, chronic inflammation, tuberculosis and pneumonia. Multivariate analysis indicated lesion appearance [solid vs. others; odds ratio (OR) 7.93; 95% confidence interval (CI) 2.94–21.40; P