Maheshwar Narayan Singh1, Arjun Lal2, Chandan Kumar Poddar3, Imtiaz Ahmad4
Tuberculous lymphadenitis is the commonest form of extrapulmonary tuberculosis and tissue diagnosis is the mainstay in the diagnosis of extrapulmonary tuberculosis. This study was conducted to compare cytology, ZN staining, fine-needle aspiration technique and culture findings of clinically suspected tuberculous lymphadenitis cases.
MATERIALS AND METHODS
This is a descriptive study. Total 300 patients of lymphadenopathy referred to the Department of Microbiology, Anugrah Narayan Magadh Medical College, Gaya, Bihar and Associated Hospital of Bihar between May 2014 and May 2017, were included. Using solid culture (BACTEC) as the gold standard, we assessed the sensitivity, specificity, positive predictive value (PPV) and negative predictive value of the FNAC for detecting MTB and ZN staining for acid-fast bacilli (AFB) respectively.
A total of 300 fine-needle aspirated specimens from lymph nodes were included in the study. Out of 300 cases, 140 aspirates were reported as cytomorphology suggestive of tuberculous lymphadenitis. The age ranged from 1 to 70 years, with the mean age of 35.5 years. Female preponderance was noted accounting for 57.14% (80/140) of cases. Maximum number of patients were from age group of 10–29 years comprising 42.15% of the group (59/140). Out of 300 cases, 68(48.57%) had lymphadenitis other than tuberculosis, and 16 (11.43%) had malignant lymphadenopathy, including 04 (02.84%) cases of primary malignancy (i.e., lymphoma) and 13 (09.28%) of secondary metastasis to lymph nodes. Though cytology suggestive of tuberculous lymphadenitis was found in 140 (46.67%) cases out of total 300 cases,Ziehl-Neelsen stain demonstrated acid-fast bacilli (AFB) in 60 (20.00%) cases and BACTEC isolated mycobacteria in 80 (26.67%) cases. When culture (BACTEC) is taken as the gold standard, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the FNAC in the diagnosis of TB lymphadenitis results was 96.55%, 96.38%, 95.89% and 96.96% as per this study and if ZN stain is taken as the standard for diagnosis, the sensitivity, specificity, PPV and NPV were 95.23%, 99.17%, 96.77% and 98.76% respectively.
FNAC is an assay which has high sensitivities when optimally selected is efficient and one of the most accurate frontline method for the diagnosis of Tuberculous Lymphadenitis. It is effectively supplemented by Ziehl-Neelsen Staining which is the most simple, quicker, reliable and relatively cheap diagnostic tool . Culture methods (BACTEC) can be reserved to obtain more accurate diagnosis.