STUDY OF EXUDATIVE PLEURAL EFFUSION IN THE AGE GROUP OF 15-40 YEARS WITH SPECIAL REFERENCE TO ADENOSINE DEAMINASE AND TUBERCULIN SKIN TEST IN THE DIAGNOSIS OF TUBERCULOUS ETIOLOGY
Authors: Banerjee Dr. Sourindra Nath , Sit Dr. Niranjan Kumar , Ghosh Dr. Santanu 
Published: July 2019

Background: A tubercular pleural effusion can either be a sequel to a primary infection acquired 3 to 6 month previously or represent reactivation tuberculousis.

Two different pathogenic mechanism can lead to tuberculous pleural effusion. By far the more common is the entry of only a few M. tuberculosis into the pleural space; in the presence of specific cell mediated immunity, tubercle bacilli provoke an intense hypersensitivity reaction and outpouring of fluid. Chest radiograph may or may not reveal associated parenchymal involvement. In the second variety, a subpleural caseous focus or cavity rupture into the pleural space and results in a pleural effusion. In this case chest radiograph nearly always shows parenchymal abnormalities.

A definitive diagnosis of TBPE can be difficult to make because of the low sensitivity and / or specificity of noninvasive traditional diagnostic tools.

 In most series of patients with TBPE the result of pleural fluid staining for acid fast bacilli are virtually always negative and pleural fluid cultures are positive for mycobacteria in <35% of cases. Without underlying lung parenchymal lesion sputum examination may be positive in 4% to 11% of patient with TBPE. On the other hand, pleural biopsy specimen will demonstrate granulomatous pleuritis in 50% to 80% of patients.

This study was taken whether pleural fluid ADA and tuberculin skin test has any role in the diagnosis of tubercular pleural effusion.

Methods and Materials: In the present study 120 cases of exudative pleural effusion in the age group of 15-40 years of varying etiology are taken who attended the pulmonary medicine department of Burdwan Medical College and Hospital.

The study was conducted the period of March 2017 to February 2018 apart from relevant history taking a detail clinical examination, full investigation were done to reach a complete and final diagnosis.

Result: In our study 120 patient of aged 15-40 years were taken. Different aetiological groups and there frequency as diagnosed by various mean were Tuberculous – 85%,  Paraneumonic effusion – 10 %, Malignant effusion – 10%.

There was male preponderance in all groups of pleural effusion. History of contact was present in 34 % cases of tuberculous effusion. Sputum for AFB was found 10.78% cases of tuberculous effusion. These patients also had pulmonary lesions. 80.39% cases of tuberculous effusion had pale yellow coloured effusion but 13.72 % cases had haemorrhagic fluid. 66.66% malignant effusion had haemorrhagic fluid and 33.37% of malignant effusion had pale yellow coloured fluid. Pleural fluid for malignant cell was positively 66.67% of malignant effusion. Pleural fluid for Z-N stain detect 1.96% cases tubercle bacilli in TBPE group. Plural biopsy was found positive in 68.18% cases of TBPE and 60% cases of MPE.

Pleural fluid ADA level was significantly higher (P<0.001) in patients of tuberculous effusion than non-tuberculous effusion. Taking a cut off value of 70 U/L sensitivity and specificity is 95.09% and 33.33%. But when parapneumonic effusion was excluded, the specificity increases. Lymphocytic pleural effusion below the age group of 40 years with cut off value of ADA <40 U/L can be used as a screening test for malignant effusion.

In TBPE tuberculin skin test was positive in 74.50% cases. Taking a cut off value of 10 mm or more induration of tuberculin skin test, "P" value is less than 0.001. Sensitivity and specificity of tuberculin skin test in tuberculous pleural effusion is 74.50% and 50%.

If we compare the efficacy of ADA > 70 U/L and tuberculin skin test positivity to diagnose tuberculous pleural effusion the former is superior statistically to the later (P value is less than 0.01) specificity of tuberculin skin test is low because it may be positive with infection with NTM and prior BCG vaccination.

Conclusion: Maximum incidence of tuberculous pleural effusion occurs in the age group of 20-30 years. Malignant pleural effusion is less likely below the age group of 30 years.

Increased ADA level >70 U/L in pleural fluid is a sensitive, minimally invasive, cost effective, easy method for diagnosis of tuberculous pleural effusion.

Lower level of pleural fluid ADA level (<40 U /L) is a sensitive, specific, minimally invasive, cost effective easy method for suspecting malignant effusion. Its value is much more important when younger patients (<40 years of age) present with malignant effusion, especially so when the pleural fluid is also appeared pale yellow. A low ADA level will guide us to look for malignancy in this age group.

Tuberculin skin testing with intermediate strength PPD has a high sensitivity in patients with pleural tuberculosis. It was seen negative in 1/3rd  cases of TBPE. This negative tuberculin skin test in TBPE may be due to recent tuberculous infection or may be due to sequestration of PPD reactive T-lymphocytes in the pleural space or patient may be anergic. Our study is insufficient to comment this negative result. More precise study need to comment.