Extrapulmonary TB (EPTB) refers to any microbiologically confirmed or clinically diagnosed case of TB involving organs other than lungs, e.g. lymph nodes, pleura, bones, joints, intestine, genitourinary tract, meninges of the brain etc.

Presumptive Extrapulmonary TB refers to the presence of organ-specific symptoms and signs like swelling of lymph nodes, pain & swelling in joints, neck stiffness, disorientation etc. They may also have constitutional symptoms like significant weight loss, persistent fever for more than two weeks, night sweats. An effort should be made to establish microbiological confirmation in case of presumptive EPTB. Appropriate specimens from the likely sites of involvement must be obtained from every presumptive EPTB patient for NAAT/smear microscopy/ culture and DST for M.tb / histopathological examination etc., based on feasibility. Chest X-ray, USG, etc., are other investigations that can be used as supportive tools for diagnosing EPTB.

Sensitivity of NAAT for M.tb detection in pus, aspirate/biopsy specimen from lymph nodes, other tissue samples, and CSF is low to moderately high but poor in pericardial, ascitic and synovial fluid samples and still poorer in pleural fluid. A positive result by culture or NAAT provides useful confirmation. However, a negative culture or NAAT cannot rule out TB due to the inadequate sensitivity of these tests in extrapulmonary specimens. Therefore, if investigations like NAAT/smear microscopy/culture, etc., turn out to be negative or if an appropriate specimen is not available for these investigations, consultation with a specialist followed by other tests, e.g. histopathology, radiology, cytology etc. may be undertaken to reach a diagnosis. Often, the diagnosis in these situations is clinically based on suggestive history, presentation and other supportive investigations. Possible alternative diagnoses must be diligently ruled out in a patient who is clinically diagnosed to have TB.