To evaluate the sensitivity of cytological examination of endobronchial biopsy, BAL, bronchial brushing and sputum in diagnosing lung carcinoma

Introduction

Johannes Müller (1801-1858), was the first, in 1838, to show cancer cells. In 1846, the same author described and illustrated cancer cells in blood-stained sputum. A French pathologist, collected specimens for cytologic examination from effusions, tracheobronchial secretion, and urine, and published his cytology atlas in 1845.1 Cytologic examination of sputum was soon introduced as routine laboratory procedure and microscopic examination of ascitic fluid was employed for diagnosis of peritoneal carcinomatosis. Malignant cells were recovered from cerebrospinal fluid in 1904 and shortly thereafter gastric washing was introduced.2

Bronchioloalveolar carcinoma is a rare subtype of lung adenocarcinoma and it has not been definitely linked to cigarette smoking. It accounts for 1-5% of primary lung cancers and can be unifocal or multifocal.3 The tumor is characterized by cuboidal or low columnar tumor cells with conspicuous nucleoli growing along pre-existing alveolar walls. It can be mucinous or nonmucinous and intranuclear cytoplasmic inclusions may be present. In sputum, small cuboidal tumor cells with oval nuclei are seen predominantly in tridimensional clusters. In materials obtained by bronchial brushing or FNA the tumor cells are commonly seen in large monolayer sheets with nuclear crowding and overlapping. Intranuclear cytoplasmic inclusions may be noted. Cells from a mucinous bronchioloalveolar carcinoma are CK7, CK20 positive and TTF1 negative. Tumor cells from a non-mucinous tumor may express surfactant proteins (SP-A, pro-SP-B, pro-SP-C).4

Materials and Methods

The present study was conducted in department of Pathology at Lok Nayak Jai Prakash Hospital, New Delhi over a period of 02 Years & One Month from March 2018 to April 2020. 343 BAL samples were received in our department, of which 216 cases were suspicious of malignancy on their clinical provisional diagnosis.

All the cases of suspected bronchial malignancy were included in present study in which broncho-alveolar lavage (BAL) and bronchial biopsy samples were received in pathology department for evaluation. Respective bronchial brushings & sputum samples were also studied where ever available.

Results

Out of 117 cases of BAL cytology, 23 (19.6%) cases were diagnosed as malignancy, 33 (28.2%) cases were of acute inflammatory infiltrate, 19 (16.2%) cases were of chronic inflammatory infiltrate, 22 (18.8%) cases were of mixed inflammatory cell infiltrate, 13 (11.1%) cases were reported as normal and 7 (5.9%) cases were found to be inadequate for any microscopic conclusion.

BAL cytology of 4 cases out of 117 initial cases, were diagnosed as malignant BAL, in which endobronchial biopsy was not helpful.

Of the 72 confirmed cases of carcinoma of lung, BAL cytodiagnosis was positive in 19 cases. Thus, in our series, the pickup rate of lung cancer by cytology was 26.3%. In 30 Squamous cell carcinoma patients, BAL cytology was positive for malignancy in 8 (26.6%) cases, for 18 cases of adenocarcinoma 5 (27.7%) cases were positive, for 10 cases of small cell carcinoma 4 (40%) were positive and for 14 cases of miscellaneous carcinoma’s of lung, 2 cases (14.2%) were positive on BAL cytology.

In our study, correctly diagnosed adenocarcinoma of lung on BAL were 27.7%, sqaumous cell carcinoma were 26.6%, small cell carcinoma were 40% and BAL cytodiagnosis from miscellaneous tumor could only be made in 14.2% cases.

Discussion

In our study sensitivity of bronchial brushing is 54.16%, which is in concordance with Cheng Wang et al5 61.9%, and with Gaber K A6 41%. Anupam Sarma7 concluded higher bronchial brushing sensitivity percentage of 87.3 and 71.43 respectively. A "false negative" finding in bronchial brushing study can be expected whenever the nylon brush is inaccurately placed or the bronchus draining the lesion is obstructed.

Comparison of the cytological characters of bronchial brushings and BAL showed that cellularity of the smear was greater in brush specimens with numerous columnar cells noted against a clear background whereas BAL samples tended to shed mostly single malignant cells with occasional cell clusters which were larger in brush than in washing samples.

In bronchial brushing the surface of the malignant lesion is scraped by the brush, the cells retrieved show better preserved morphological details in comparison to the cells which have already exfoliated into the bronchial cavity. Thus this technique manages to 'dislodge' the cells from the surface of those well­ differentiated malignant lesions too, which do not exfoliate cells readily. Thus, the chances of getting adequate diagnostic cytological sample by BB greatly increase in comparison to BAL samplings. Bronchial brushing is a much superior technique in the diagnosis and morphological typing of lung cancers, as it demonstrates far better Specificity, Sensitivity and Accuracy, in comparison to BAL.8

Sputum cytology was positive in 1 of 3 confirmed cases of carcinoma lung. Thus, the sensitivity (pick up rate) was 33.3% this is comparable with that of 31.6% of Choi Y D9 study, 36% in case of Gledhill A10 study, 40% in case of Sing A11 study and 45.3% in Khalid M12 study.

Conclusion

Endobronchial biopsy and BAL, both were studied, sensitivity of cases increases and number of false negative cases decreases for diagnosis. Bronchial brushing has better sensitivity than BAL for diagnosis of lung carcinoma. Sputum is less sensitive than bronchial brushing for diagnosis of lung carcinoma.

Source of Funding

None.

Conflict of Interest

The authors declare that there is no conflict of interest.