Evaluation of polymerase chain reaction in space-occupying lesions of liver reported as granulomatous inflammation/tuberculosis on fine-needle aspiration cytology

Abstract

Background: Tubercular involvement of the liver is uncommon, but is a serious consideration in differential diagnosis of granulomatous conditions, especially in endemic regions like India. Objective: To assess the role of polymerase chain reaction (PCR) done on archival cytological material in diagnosing tuberculosis (TB) in cases reported as granulomatous inflammation/TB in liver lesions. Materials and Methods: This was a retrospective study including a total of 17 cases of liver space-occupying lesions (SOLs) reported as granulomatous inflammation (n = 12) and TB (n = 5). The smears were retrieved from the archives of the department and were reviewed for the cytomorphologic features. Air-dried smears stained with May–Grünwald–Giemsa (MGG) stain were assessed for the representative material in the form of epithelioid granulomas and giant cells. One/two MGG smears from each case were destained and the material was used for performing PCR for Mycobacterium tuberculosis by amplification of 123 bp fragment of the IS6110 insertion element. Results: The age of the patients ranged from 3 to 61 years. There were 12 females and 5 males. The patients presented with solitary/multiple liver SOLs. DNA could be extracted from 10/17 cases from archival MGG smears. PCR positivity was noted in 8/10 cases (including four acid-fast bacilli smear-positive cases), confirming a diagnosis of TB. Conclusion: Cytomorphology alone may not be sufficient for differentiating various granulomatous lesions reported in liver SOLs. DNA can be extracted from the archival cytological MGG-stained smears. PCR should be carried out if Ziehl–Neelsen staining is negative in granulomatous lesions, especially when material has not been submitted for culture.