Cellular analysis of bronchoalveolar lavage uid in various lung lesions

BAL provides a safe and generally welltolerated means of retrieving secretions that coat the surfaces of the bronchial and alveolar epithelium [1]. Cellular analysis of bronchoalveolar lavage uid in various lung lesions Punyashetty KB.1, Solanki PS.2*, Anand SA.3 DOI: https://doi.org/10.17511/jopm.2020.i02.09 1 Kajal B. Punyashetty, Professor, Department of Pathology, Navodaya Medical College, Raichur, Karnataka, India. 2* Padma Shree Solanki, Third-year Postgraduate student, Department of Pathology, Navodaya Medical College, Raichur, Karnataka, India. 3 Anand A. S., Professor and Head, Department of Pathology, Navodaya Medical College, Raichur, Karnataka, India.

It is a convenient procedure to apply for the diagnosis of diffuse parenchymal lung diseases [2].
It is less invasive than transbronchial and open lung biopsies and has great clinical value. Therefore, it is designated by some specialists as "liquid biopsy" [3].
The cellular analysis of BAL fluid includes total and differential cell counts and is a part of clinical routine [4]. BAL nucleated immune cell patterns that deviate from that observed in normal individuals (80-90% alveolar macrophages, 5-15% lymphocytes, ≤3% neutrophils, ≤1% eosinophils) are indicative of an inflammatory/ infiltrative process that has perturbed the lung airways and/or interstitium [5].
The predictive value of BAL differentials are reported to make some diagnosis more likely and exclude others [2]. Thus, BAL can provide a useful tool for the diagnosis of lung diseases when combined with aspects of clinical presentation and HRCT scanning [1].
Cell counting of BAL fluid is performed manually in routine practice. This has both methodological and inherent errors. This study utilizes an electronic automated counting device that offers a quick, precise and simple method for counting cells in unprocessed BAL fluid which is both less laborintensive and subjective than manual counting [6]. The sample was also centrifuged and sediment was smeared. The smears were prefixed with 95% methanol and air-dried. Methanol fixed samples were stained using Papanicolaou stain. The air-dried samples were stained with Leishman stain and MGG (May-Grunwald Giemsa). Differential cell counts that included percentages of neutrophils, lymphocytes, alveolar macrophages, and eosinophils were also determined using these smeared slides.

Exclusion Criteria
Patients who were treated with antimicrobial agents for more than 24 hours before bronchoscopic BAL.

Results
The present study involved cellular analysis of BAL All cases which were having an indication for bronchoscopy were included.
Cases with chronic obstructive lung diseases are contraindicated for bronchoscopy and thus were excluded by default in this study.
Pediatric age group (birth to 17 years) and patients above 80 years of age were excluded in the study.
Tropical Journal of Pathology and Microbiology 2020;6(2) There was a significantly higher number of smokers (16 cases) among the male population contributing to 43.2% of the total study population. None of the female patients (16 cases) were smokers (Table 2). The total WBC count ranged from 31 cells/µl to 94 cells/µl. The maximum increase in total WBC count was seen in cases of asthma. The minimum WBC count was seen in cases of pneumoconiosis (Table   3).    [12].
Increased eosinophils can be seen in many forms of ILD but their numbers on differential cell count usually do not exceed 10%. An eosinophil differential count greater than or equal to 25% in a patient is highly likely to be caused by eosinophilic in BAL fluid analysis of asthmatic patients [13].
There were two cases of adenocarcinoma and one case of squamous cell carcinoma in the present study. In non-hematological malignancies of the lung, there is an increase in the number of monocytes in BAL fluid [14].In the present study, The proportion of mononuclear cells on the SYSMEX XNL/350 six-part analyzer was 78%. This is consistent with the study of Sampsonas F et al on BAL fluid samples from 92 cases of nonhematological malignancies showing an increase in the proportion of monocytes (74%) [14].
In more rare diseases, the potential diagnostic value of BAL cell differentials must be combined with additional clinical and radiographic information to help secure a confident diagnosis and obviate the need to proceed to the more invasive procedure of surgical lung biopsy which is associated with significantly increased risk of morbidity and mortality [3,4].
Automated hematology systems enable a rapid and reliable determination of leukocyte subsets in BAL fluid. Clinicians could make use of BAL fluid cellular profiles to make therapeutic decisions, such as choosing the appropriate site of care or the level of patient monitoring [15].

Limitations of the study:
The present study acknowledged the weakness of the study is a small sample size. Larger sample size could have yielded more useful data. Also, the six-part analyzer provides a differential cell count only in terms of mononuclear and polymorphonuclear cells but does not provide a complete differential cell count as obtained using sediment smear slides of the BAL fluid.

Conclusion
Bronchoalveolar lavage is a widely used primary technique for suspected lung disease patients. Although BAL differential cell counts are not specific markers of diseases, they provide substantial diagnostic information in frequent lung diseases.
What does the study add to the existing knowledge?
BAL fluid analysis on automated analyzer along with detailed cytology aids to increased diagnostic accuracy in various lung diseases.