Tubercular Lymphadenitis and Abdominal Tuberculosis
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Direct answer
Tubercular lymphadenitis is Mycobacterium tuberculosis infection of lymph nodes, most often in the neck, where it presents as painless, matted nodes that may form cold abscesses and sinuses, a picture called scrofula. Abdominal tuberculosis, especially ileocaecal disease and tubercular peritonitis, is supported by a lymphocyte-predominant ascitic fluid, a low serum-ascites albumin gradient and a raised ascitic adenosine deaminase, with biopsy confirming caseating granulomas.
What you must remember
- Scrofula: Painless, matted cervical nodes that may form cold abscesses and sinuses, with fine needle aspiration showing caseating granulomas.
- Lymphadenitis treatment: Follows the standard six-month NTEP regimen, with an intensive phase of four drugs (HRZE) for two months and a continuation phase of three drugs (HRE) for four months.
- Ileocaecal tuberculosis: Right iliac fossa pain, weight loss and a mass that can mimic Crohn disease, with colonoscopy biopsy showing caseating granulomas.
- Tubercular peritonitis: A lymphocyte-predominant exudate with a serum-ascites albumin gradient below 1.1 g/dL, the cut-off that separates non-portal-hypertensive ascites from portal-hypertensive ascites.
- Ascitic ADA: A raised adenosine deaminase supports the diagnosis, with commonly used cut-offs in the 30 to 40 U/L range, but lymphoma and other conditions can also raise it.
- Laparoscopy: Peritoneal nodules and biopsy give the highest yield when fluid studies are not diagnostic.
A worked pathway: ascites with weight loss
Consider a 26-year-old woman with weight loss, low-grade evening fever and abdominal distension. Ascitic fluid shows a lymphocyte-predominant exudate, and the serum-ascites albumin gradient is low, pointing away from portal hypertension. Ascitic adenosine deaminase is raised, and GeneXpert on the ascitic fluid is sent, although its sensitivity in fluid is limited, so a negative result does not exclude TB. Laparoscopy shows peritoneal nodules, and biopsy reveals caseating granulomas, which confirms the diagnosis. Anti-tubercular treatment begins under the NTEP framework, with liver function monitored because hepatotoxicity is a major concern. Adjunctive corticosteroids are sometimes used in selected cases, decided individually. For a separate patient with a right iliac fossa mass and fever, the same logic applies: colonoscopy and biopsy separate caseating ileocaecal TB from Crohn disease, and sputum and chest imaging look for pulmonary co-disease. Once the diagnosis is secured, the team counsels the patient about adherence to the six-month course, regular liver function checks and completing treatment even when she feels well. Contact screening is offered to household members, and the case is notified under the NTEP, which is mandatory under the programme.
Where the exam tries to catch you
The exam favours the differential rather than a single diagnosis. A raised ADA in ascitic fluid is not specific, since lymphoma and other lymphocytic conditions also raise it, so the whole vignette must be read. The albumin gradient is the key separator: a low gradient suggests peritoneal disease such as TB or carcinomatosis, whereas a high gradient points to portal hypertension. Scrofula is also confused with lymphoma and sarcoidosis, and the absence of systemic symptoms does not exclude TB. In ileocaecal disease, the classic contrast with Crohn disease is caseating granulomas on biopsy, and the classic radiological feature is caecal involvement without skip lesions. The first-line regimen is the same for lymphadenitis and abdominal TB, so the examiner's question is usually about diagnosis rather than treatment.
Frequently asked questions
Which ascitic fluid findings favour tubercular peritonitis?
A lymphocyte-predominant exudate with a serum-ascites albumin gradient below about 1.1 g/dL and a raised ascitic adenosine deaminase favour tubercular peritonitis. Because these markers are not fully specific, peritoneal biopsy or laparoscopy is often needed to confirm the diagnosis.
How is scrofula diagnosed?
Scrofula is diagnosed by fine needle aspiration cytology showing caseating granulomas with acid-fast bacilli, supported by culture or molecular testing of the aspirate. Excision biopsy is reserved for cases where aspiration is non-diagnostic, and lymphoma must be excluded by histology.
What distinguishes ileocaecal tuberculosis from Crohn disease?
Ileocaecal tuberculosis tends to show caecal ulceration and caseating granulomas on biopsy, with disease usually confined to a segment. Crohn disease shows skip lesions and non-caseating granulomas, so histology is the key to the distinction.
How long is treatment for tubercular lymphadenitis?
Tubercular lymphadenitis generally follows the standard six-month NTEP regimen, with two months of an intensive four-drug phase (HRZE) and four months of continuation with three drugs (HRE). Central nervous system and bone tuberculosis are treated for longer, so the site of disease always matters for duration.