A rare case of Pancreatic Tuberculosis - A Case Report
Associate professor1, Professor2, Professor and Head4, Department of Pathology, and Professor and Head3, Department of Radiodiagnosis, Kamineni Academy of Medical Sciences and Research Centre, LB Nagar, Hyderabad, Telangana State, India.
Tuberculosis (TB) is an extremely common disease in developing countries, though its incidence is on the rise in western world too. TB of digestive system involves ileocecal region commonly, followed by regional lymph nodes. Atypical form of TB is commonly seen with immunocompromised patients.1 Pancreatic TB is considered a very rare clinical entity, although in postmortem studies pancreatic involvement was seen in 0 to 14% of deaths from miliary Increased incidence of this entity is related now to frequency of abdominal tuberculosis in immunocompromised patients and improvement in the imaging modalities of pancreas.4
Fine Needle Aspiration Cytology (FNAC) is a sensitive and rapid method in diagnosing pancreatic TB. Pancreatic TB should be considered as a differential diagnosis of a pancreatic mass in immunocompromised patients and most patients have good response to anti-tuberculosis treatment.
A 35 year old female patient, retro viral (HIV) positive, presented to the outpatient department with complaints of fever on and off since one month, pain abdomen of twenty days duration and mass per abdomen noticed four days back. The patient underwent ultrasonographic (USG) examination of abdomen. USG revealed a well circumscribed irregular cystic lesion containing anechoic fluid and internal debris in head and the body of pancreas and extending outside. Subsequently the patient underwent Computerized Tomography (CT) scan, which revealed a hypodense lesion in the head and body of pancreas (Fig. 1).
Differential diagnosis such as cystic neoplasm of pancreas, pseudo-cyst of pancreas, and pancreatic abscess were considered. USG guided FNAC was performed under strict aseptic conditions using an 18 gauge spinal needle. The aspirate revealed frank, thick pus, and the material was smeared on slides and stained with May-Grunwald-Giemsa (MGG) stain, and Ziehl-Neelsen (ZN) stain for acid fast bacilli (AFB). The smear showed degenerative / necrotic background loaded with acid fast bacilli on ZN stain (Fig. 2).
Tuberculosis (TB) in its extra-pulmonary form rarely affects pancreas, because it is biologically protected from Mycobacterium tuberculosis bacilli due to presence of pancreatic enzymes.5 Most of the medical literature on this rare disease is limited to case reports or small case series. Most cases of pancreatic TB arise from contiguous infection from peripancreatic lymph nodes or directly from hematogenous spread or reactivation of previous abdominal TB.6.7 Clinical features of TB are nonspecific. A meta-analysis of twelve published reports by Lo et al,8 listed constitutional symptoms like weight loss, fever, malaise, night sweats, epigastric pain, nausea, diarrhea and obstructive jaundice as the most common symptoms. CT scan may demonstrate focal hypodense lesion, diffuse enlargement of pancreas, but none of them are pathognomonic of TB. Ring enhancement or low density areas within enlarged lymph nodes should make one suspect TB lymph nodes.9 Percutaneous image guided FNAC of suspected lesions might suggest the diagnosis of TB, there by obviating the need for diagnostic laparotomy or pancreatic resection.6,10 In almost half of the patients with extra-pulmonary tuberculosis, ZN staining for AFB and prolonged culture for mycobacterium tuberculosis has been found to be negative.11 Very few are diagnosed by FNAC.
A high index of suspicion must be maintained for pancreatic TB in immunocompromised patients who are presenting with mass abdomen or hypodense lymph nodes in peri-pancreatic region. When diagnosis is suspected, a detailed screening for TB and image-guided FNAC of pancreatic lesion can confirm the diagnosis and unnecessary explorative laparotomy or pancreatic resection can be avoided.
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