An uncommon case of gall bladder mass: gall bladder tuberculosis

Introduction

Tuberculosis (TB) is very common disease in India, where it accounts for more than one-quarter of the global burden of this disease. ¹ Abdominal TB is an important form of extrapulmonary tuberculosis (EPTB) accounting for >10% of cases. However, gall bladder TB is a rare entity, with only a few more than 100 cases reported in the literature. ² The preoperative differentiation of gall bladder TB from malignancy is difficult. Occasionally, it may be diagnosed incidentally by needle biopsy. We report an unusual case diagnosed where metastatic gall bladder cancer was suspected.

Case report

A 49-year-old woman with no known co-morbidity presented with a history of right upper abdominal pain and dyspepsia for 12 years. Gallstone disease was diagnosed in a local hospital and laparoscopic cholecystectomy was recommended two years before. The procedure was, however, abandoned owing to dense adhesions in Calot’s triangle. She complained of an increase in frequency and severity of her pre-existing right upper abdominal pain and significant weight loss. Abdominal examination revealed a palpable gall bladder mass without hepatomegaly or ascites. Abdominal ultrasonography and computed tomography (CT) scanning showed a gall bladder with a few calculi 15 mm in diameter within its lumen and its fundus to be replaced by a well-defined hypodense mass which was infiltrating the adjacent liver. There were multiple enlarged lymph nodes seen in the porta hepatis (Figure 1). OPEN IN VIEWER

Positron emission tomographic (PET) scan revealed intense uptake in the asymmetrical thickening of the gall bladder wall, periportal lymph nodes and omentum (Figure 1), suggestive of malignancy. Ultrasound-guided fine needle aspiration cytology (FNAC) was performed on the gall bladder mass, which revealed caseating necrosis, degenerating inflammatory cells and a few benign mesothelial cell clusters. Ziehl-Nielsen stain for acid fast bacilli was positive suggesting TB (Figure 2). Standard four-drug anti-tubercular treatment (ATT) with rifampin, isoniazid, pyrazinamide and ethambutol was started. OPEN IN VIEWER

Discussion

Gall bladder TB is a rare entity and usually occurs along with other co-existing intra-abdominal TB, reaching the gall bladder directly, or via lymphatics, peritoneal fluid or the blood stream. ² A possible inhibitory effect of bile may be the reason for TB to be rare in the biliary system. Gallstones blocking the cystic duct may therefore be an important factor allowing for TB infection. ³ Gallstone disease is found in 70% of cases of gallbladder TB. ³ However, TB in a normal-looking gall bladder wall and mucosa has also been reported. ⁴ Gall bladder TB has been found with miliary TB, disseminated abdominal TB, isolated TB and with immunodeficiency. ⁵

Gall bladder TB poses a significant diagnostic challenge. Patients may present with symptoms mimicking carcinoma or chronic cholecystitis. ⁶ A conclusive diagnosis is only possible by histopathological examination of resected specimen or tissue or FNAC.

Radiology is an important tool in evaluating gall bladder pathology. However, there are no reported pathognomonic features on radiology which can reliably differentiate gall bladder malignancy from TB. ⁷ All three types of CT morphology described ⁸ have been seen with TB. Furthermore, a PET scan, although usually a reliable tool for detecting malignancy may prove a false positive, as in our case. ⁹

Preoperative diagnosis of gall bladder TB is difficult but a high index of suspicion should always remain, particularly in endemic areas. High-risk patients include those with a previous history of pulmonary or extra pulmonary TB, or immunosuppression. ⁶

Radical cholecystectomy is the recommended treatment for resectable gallbladder cancer. ⁶ The diagnosis should be made before abdominal intervention to prevent loco-regional spread. A diagnosis by needle biopsy or cytology is recommended ¹⁰ and is preferable to frozen section tissue diagnosis at laparotomy. ¹¹ The practice of routine cholecystectomy where tissues are adherent and may be involved by malignancy is to be condemned. Thus, because gall bladder TB and malignancy are virtually indistinguishable, a preoperative diagnosis is worth chasing.

Conclusion

Gallbladder TB mimics gall bladder malignancy. In patients with a gall bladder mass, a diagnosis of gall bladder TB should be considered.