DS Gaur, NC Thapliyal, S Kishore, VP Pathak
Department of Pathology, Himalayan Institute of Medical Sciences, Jolly Grant, Dehradun - 248140, Uttaranchal, India

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Abstract

Of all the cases investigated for suspected lung cancer between June 1999 and June 2003, 196 cases were selected where flexible bronchoscopic samples of broncho-alveolar lavage (BAL) and bronchial brush (BB) cytology as well as bronchial biopsy were taken and processed as per standard procedures of cytology and histology. The aim of this study was to compare the diagnostic efficacy of BAL and BB cytology in diagnosing lung cancer, taking bronchial biopsy as the 'Gold Standard' diagnostic test. Sensitivity of BB was 87.3%; while that of BAL was 39.4%. Specificity of BB and BAL was 97.6% and 89.6%, respectively. BB was better than BAL in morphological typing of lung cancers. We conclude that bronchial brushing is a much superior technique in the diagnosis and morphological typing of lung cancers.

Keywords: Bronchial brushing, broncho-alveolar lavage, diagnostic efficacy, lung cancer

Introduction

Materials and Methods

Observations

cytology showed 62 True Positive cases and 122 True Negative cases with only 03 cases as False Positive and 09 cases as False Negative [Table 2].

Sensitivity of cytodiagnostic results of BB was 87.3%; while that of BAL was only 39.4%. Specificity of BB was 97.6% and that of BAL was 89.6%. Similarly Positive Predictive Value and Negative Predictive Value, False Negative Index and False Positive Index of BB were better than of BAL. Accuracy of brush cytology was 93.9% while that of BAL was 71.4% [Table 3].

Twenty (71.4%) of the 28 cases diagnosed by BAL as lung cancer, were morphologically classified as poorly differentiated carcinoma. Similarly 33 (53.2%) of the 62 cases diagnosed by BB as lung cancer, were morphologically classified as poorly differentiated carcinoma. While only 26 (36.6%) cases out of 71 bronchial biopsies, were labeled as poorly­differentiated carcinomas. Thus biopsy specimens showed much better morphological features and helped in categorizing these cases into specific type of carcinomas in comparison to the cytological material obtained by either BAL or BB [Table 4].

Discussion

With the advent of flexible fiber-optic bronchoscope, respiratory cytology took a new turn as samples like bronchial washings, bronchial brushings, broncho-alveolar lavage and trans-bronchial needle aspirations could be collected from the respiratory tract, yielding significant amount of cytological material. ^[1] With this, the emphasis shifted from diagnosis of malignancy in operable patients and confirmation of metastases, to the use of cytology as a first line diagnostic procedure on which crucial management decisions could be based. ^[1],[3]

In our study, in comparison to BAL, bronchial brushing gave higher number of True Positive and True Negative cases, and much lesser number of False Positive and False Negative cases, showing its superiority over BAL in diagnosing lung cancers [Table 2].

Since cytological sampling by BAL technique relies mainly on cells 'exfoliated' from the malignant lesion in the bronchial epithelium, the adequacy of its samples depends on several vital factors, especially a) the degree of differentiation of malignant growth; b) preservation of the morphology of cytological material obtained; and c) technical skill of the pulmonologist who is retrieving the lavage fluid from the bronchus [Figure 1] & [Figure 2]. In general, less differentiated, anaplastic lesions have more loosely cohesive cells in comparison to well differentiated lesions. ^[3] Thus such lesions exfoliate larger number of cells into the bronchial cavity than the well­differentiated lesions. Secondly, while these exfoliated cells are lying in the bronchus, they start developing degenerative changes, thus progressively losing their morphological details which are important in differentiating them from non-malignant cells shed­ off by the normal bronchial epithelial lining. Usually around 20ml. saline is instilled through the bronchoscope for BAL samples. ^[1] If the technique of the pulmonologist is not proper, the sample retrieved might be less in amount and thus may have lesser cytological material than expected, thus again increasing the chances of false negative results. ^[1],[4] All these factors, present individually or together, affect the overall yield and diagnostic value of BAL specimens.

Bronchial brushing technique has the advantage that the surface of the suspicious lesion is scraped by the help of a brush passed in through the bronchoscope. ^[1] Thus this technique manages to 'dislodge' the cells from the surface of those well­differentiated 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 [Figure 3] & [Figure 4]. Moreover, since 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 [Figure 2] & [Figure 4]. All these factors contribute in the increased diagnostic yield of BB samplings.

In our study, the Sensitivity, Specificity and Accuracy of BAL samples were 39.4%, 89.6% and 71.4% respectively, when a single sample of BAL was collected [Table 3]. Truong et al ^[4] reported Sensitivity of 66.0%; while Ng. & Horak ^[5] reported a Sensitivity as high as 74.0% for BAL. Studies have shown that increasing the number of attempts at obtaining BAL sampling can improve its Sensitivity, Specificity and Accuracy. ^[4],[6],[7] However, the inconvenience caused to the patient, in spite of BAL technique being non­invasive, outweighs the benefits of multiple samplings, especially when other techniques like bronchial brushing and bronchial biopsy are available.

In our study, the values of Sensitivity, Specificity and overall Accuracy of BB were 87.3 %, 97.6 % and 93.9 % respectively, which were much superior to those of BAL [Table 3]. The Sensitivity of 87.3% for BB in our study was in agreement with various other workers like Chopra et al ^[8] (86.3%); Zavala et al ^[9] (88.5%); and Solomon et al ^[10] (89.1%). Shroff et al ^[11] reported the Sensitivity of BB to be as high as 97.3% in their study. Bibbo et al ^[12] reported the Sensitivity for BB samples to be only 70%. However they reported the Specificity of BB to be much higher (98%) which was comparable to our study.

Various workers have tried to combine the two techniques of BB and BAL, in order to improve the yield of diagnostic cytological material. Govert et al ^[13] reported 85.3% Sensitivity on combining these two techniques; while Bedrossian et al ^[14] reported a higher Sensitivity of 92%. However, this combination has not gained much popularity due to the fact that in doing so, instead of one, the cost of two cytological procedures needs to be borne by the laboratory or the patient, for a little improvement in Sensitivity, when compared with results of BB alone. ^[13]

In the present study, bronchial biopsy classified 29.6% cases (n=21/ 71) as squamous cell carcinoma. While BB could diagnose 22.6% of the cases (n=14/ 62) as squamous cell carcinoma, BAL was able to diagnose only 17.9% cases (n=5/ 28) as squamous cell type. Similarly, 19.7% cases (n=14/71) were diagnosed as small cell carcinoma by biopsy. BB samples classified 14.5% cases (n=9/62) as small cell carcinoma while in BAL samples only 7.1% cases (n=2/ 28) were morphologically diagnosed as small cell type. Thus it was obvious that samples obtained by BB showed better cytological details than BAL, which helped in the specific morphological classification of lung cancers.

A large number of samples of BB (53.2%) were classified as poorly differentiated carcinoma, indicating that BB still remained inferior to biopsy, where morphological classification was required. Biopsy samples showed only 36.6% cases to be poorly differentiated carcinomas; while rest could be specifically categorized as, squamous, small cell or other types. With BAL, due to less demonstrable cytological details, as many as 71.4% samples got classified as poorly differentiated carcinoma. Thus, BB showed superiority over BAL in morphological classification of malignant samples [Table 4].

With a good Sensitivity (87.3 %), Specificity (97.6 %) and Accuracy (93.9 %), bronchial brushing promises to be a very convenient cytological technique that can be confidently utilized for screening of doubtful cases and early diagnosis of lung cancer, as it saves the time needed for the processing of biopsy specimens. However, as BB falls short of expectations in morphological classification of lung cancers, only cases positive for malignancy may later be biopsied to confirm the morphological type of the malignant lesion.

Conclusion

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 broncho­alveolar lavage.

 

References

1.	Johnston WW, Elson CE. Respiratory tract. In: Bibbo M, editor. Comprehensive cytopathology. 2nd ed. Philadelphia: W.B. Saunders Company; 1997. p. 325-401.
2.	Bancroft JD, Gamble M, editors. Theory and practice of histological techniques. 5th ed. New York: Churchill Living Stone; 2002.
3.	Husain AN. The lung. In: Kumar V, Abbas AK, Fausto N, editors. Robbins and Cotran pathologic basis of disease. 7th ed. India: Saunders; 2004. p. 711-72.
4.	Truong LD, Underwood RD, Greenberg SD, McLarty JW. Diagnosis and typing of lung carcinomas by cytopathologic methods. A review of 108 cases. Acta Cytol 1985; 29:379-84.
5.	Ng ABP, Horak GC. Factors significant in the diagnostic accuracy of lung cytology in bronchial washing and sputum samples: II. Sputum samples. Acta Cytol 1983; 27: 397-402.
6.	Ahmad M, Afzal S, Saeed W, et al. Efficacy of bronchial wash cytology and its correlation with biopsy in lung tumours. J Pak Med Assoc 2004; 54:13-6.    [PUBMED]
7.	Naryshkin S, Daniels J, Young NA. Diagnostic correlation of fiberoptic bronchoscopic biopsy and bronchoscopic cytology performed simultaneously. Diagn Cytopathol 1992; 8:119-23.    [PUBMED]
8.	Chopra SK, Genovesi MG, Simmons DH, Gothe B. Fiberoptic bronchoscopy in the diagnosis of lung cancer comparision of pre and pro bronchoscopy sputa, washings, brushings and biopsies. Chest 1997; 111:522-3.
9.	Zavala C: Diagnostic fiberoptic bronchoscopy. Techniques and results in 600 patients. Chest 1975; 68:12-9.
10.	Solomon DA, Solliday NH, Gracey DR. Cytology in fiberoptic bronchoscopy: comparison of bronchial brushing, washing and post-bronchoscopy sputum. Chest 1974; 65:616-9.    [PUBMED]  [FULLTEXT]
11.	Shroff CP. Abrasive bronchial brushing cytology. A preliminary study of 200 specimens for the diagnosis of neoplastic and non-neoplastic broncho-pulmonary lesions. Acta Cytol 1985; 29:101-7.
12.	Bibbo M, Fennessy JJ, Lu CT. Bronchial brushing technique for the cytologic diagnosis of peripheral lung lesions: a review of 693 cases. Acta Cytol 1973; 17:245-51.
13.	Govert JA, Kopita JM, Matchar D, Kussin PS, SamuelsonWM. Cost effectiveness of collecting routine cytologic specimens during fiberoptic bronchoscopic for endoscopically visible lung tumours. Pol Arch Med Wewn 2002; 108:1193-7.
14.	Bedrossian CWM, Rybka DL. Bronchial brushing during fiberoptic bronchoscopy for the cytodiagnosis of lung cancer: comparison with sputum and bronchial washings. Acta Cytol 1976; 20:446­53.

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Correspondence Address:
D S Gaur
Department of Pathology, Himalayan Institute of Medical Sciences, Jolly Grant, Dehradun - 248140, Uttaranchal
India

Source of Support: None, Conflict of Interest: None

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Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 

Tables

  [Table 1], [Table 2], [Table 3], [Table 4]