Transbronchial brushing cytology and paired biopsy in endobronchial tuberculosis: A report of 72 cases focusing on the morphological features

The objectives of this study were to review the transbronchial brushing cytology and histological specimens of endobronchial tuberculosis (EBTB) and to explore the morphological features, diagnostic pitfalls, and dilemmas. Transbronchial brushing cytology and concurrent biopsy specimens obtained between July 2017 and June 2020 were reviewed. EBTB was confirmed based on the clinical response to the anti-TB treatment in addition to the positive findings of at least one of the following methods: Acid-fast bacilli stain (AFB), auramine-rhodamine stain (A-R), detection of TB bacterial DNA (TB-DNA) by polymerase chain reaction, T-cell spot test (T-spot), and typical pathologic changes of TB on cytology or bronchoscopy biopsy. A total of 72 confirmed cases were studied. Of the 72 patients, 42/72 (58.3%) and 30/72 (41.7%) were female and male patients, respectively. Bronchoscopic findings revealed five subtypes of EBTB, including inflammation infiltration, ulceration necrosis, granulation hyperplasia, cicatrices stricture, and tracheobronchial malacia. AFB, A-R, TB-DNA, and T-spot were positive in 39, 26, 33, and 46 cases, respectively. The detection rate of necrosis in the cytological specimens (90.3%) was significantly higher than that in the biopsy specimens (77.8%; P < 0.01). The percentage of Langhans giant cells detected by cytology (13.9%) was significantly lower than that detected by the pathological examinations of the tissues (38.9%) (P < 0.01). The detection rates of metaplastic squamous cells and epithelioid cells showed no significant difference with respect to the cytology and biopsy findings. In addition to the two patients who had concurrent carcinomas, atypical cells were reported in nine patients through cytopathological diagnosis, among them two were suspected to have carcinomas, two were with the impression that spindle cell neoplasms could not be excluded, and the other five were considered as reactive atypia. Moreover, one biopsy could not rule out the well-differentiated squamous cell carcinoma. Some morphological variations may cause challenges in cytological evaluation. Moreover, diagnostic dilemmas can occur even in the assessments of tissue pathology.