Tuberculous peritonitis diagnosed with the help of 18 F‐FDG PET/CT scan

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Mycobaterium tuberculosis accounts for 4.47 % of all peritonitis episodes in peritoneal dialysis patients. In one of the reviews,1 the treatment delay was identified as a significant factor for mortality in patients with tuberculous peritonitis. The peritoneal dialysate cell count could not be solely used to differentiate tuberculous peritonitis from other forms of peritonitis.2 Many methods such as culture, smear, biopsy, and polymerase chain reaction (PCR) are useful in the diagnosis of peritoneal tuberculosis.3 But low sensitivity of these methods is an impediment. We used 18 F‐fluorodeoxyglucose positron emission tomography/computerized tomography (18 F‐ FDG PET/CT) scan to help in diagnosis of tuberculous peritonitis in three patients.
The first patient was a 35‐year‐old male with diabetes and hypertension who underwent peritoneal dialysis catheter insertion approximately 8 months ago for end stage renal disease. He was on automated peritoneal dialysis. He presented with complaint of fever of 1 week duration. The fever was of low grade, intermittent, associated with evening rise of temperature and had not subsided with antipyretics. There was history of abdomen pain and cloudy dialysate of 4 days duration.
On admission the patient had pallor and no palpable lymph nodes. His abdomen was tender. Dialysate was cloudy on the day of admission. There was no evidence of exit site or tunnel infection. He was started on intraperitoneal antibiotics after sending specimens for investigations. The dialysate total leucocyte cell count on first 3 days was 420, 320 and 280 cells/μL. The differential count was 85% lymphocytes on day 1, and 100% lymphocytes on days 2 and 3. Gram and Ziehl‐Neelsen stains of dialysate fluid revealed no organisms. Cultures of dialysate and PCR for tuberculosis sent on days 1 and 3 yielded negative results.
With a suspicion of tuberculosis, 18 F‐FDG PET/CT scan was performed. It revealed metabolically active pre‐ tracheal, para‐tracheal and pre‐vascular lymphadenopathy (Fig.1). The cytology of the pre‐tracheal lymphnode showed caseating granuoma. The patient was started on antituberculosis drugs on day 4. He was treated with isoniazid (5 mg/kg per day), rifampin (10 mg/kg per day), pyrazinamide (10 mg/kg per day) and levofloxacin (15 mg/kg per alternate day). Within 24 h there was clearing of the dialysate. The total leucocyte count decreased from 100 to 10 cells/μL by day 7. After 4 weeks, the culture of the dialysate sent on the day of admission had shown Mycobacteria tuberculosis on the Lowenstein Jensen medium. We treated two more patients for tuberculosis peritonitis with the help of 18 F‐FDG PET/CT scan (Suppl. Table S1). In regions with high prevalence of tuberculosis in the general population, 18 F‐ FDG PET/CT scan might help to find lymphadenopathy that could not be found on other imaging. The pathology of these lymph nodes yields the diagnosis of tuberculosis. Immediate anti‐tuberculosis therapy might help to retain the peritoneal dialysis catheter.
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