Atypical mycobacterial infection mimicking metastatic cholangiocarcinoma
A previously fit and healthy 45-year-old Caucasian female presented to our unit with history of jaundice, mild upper abdominal discomfort and weight loss. She had undergone a laparoscopic cholecystectomy 5 years ago followed by an endoscopic retrograde cholangiopancreatography (ERCP) to extract a common bile duct (CBD) calculus. There was no history of overseas travel or contact with patients with tuberculosis.\nThe liver function tests revealed an obstructive picture. Bilirubin level was 86 µmol/l (normal 2–24 µmol/l). Gamma glutamyl transferase (GGT) and alkaline phosphatase were 347 and 340 U/l, respectively. In view of prior history of choledocolithiasis, an ERCP was undertaken. An eccentric stricture at the level of the junction of cystic duct and CBD was seen along with a dilatation of proximal the bile duct. There were no ductal calculi. A plastic stent was inserted to relieve the jaundice (Fig. ). These findings raised the suspicion of a malignant process, and a computerized tomography (CT) scan of the chest, abdomen and pelvis was consequently performed.\nThe CT scan revealed multiple hypodense liver lesions predominantly in the right lobe of the liver (Segment 6 and 8) highly suspicious of metastatic deposits (Fig. ). A preliminary diagnosis of metastatic cholangiocarcinoma was made on this basis.\nThe case was discussed in the multidisciplinary meeting and decision was taken to attempt a percutaneous biopsy of the liver lesions to confirm the diagnosis and plan for palliative chemotherapy.\nAn ultrasound-guided core biopsy was attempted, but failed due to technical reasons. A CT-guided core biopsy of Segment 6 lesion was successful, but an interval reduction in the size of the liver lesions was noted. A magnetic resonance cholangiopancreatography (MRCP) to reassess the liver and biliary tree was therefore planned. MRCP revealed a persistent stricture at the cystic duct CBD junction (Fig. ). The histology from the core biopsies of the liver revealed a granulomatous process with Langhans giant cells (Fig. ). The pathologists opined that although rare, mycobacterial involvement should be considered as a differential diagnosis. This coupled with the spontaneous reduction in the size of the liver lesions led to a consensus opinion for a surgical exploration to resect the biliary stricture and re-biopsy the liver lesions.\nAt surgery multiple liver lesions were evident and two of these were biopsied. A fibrotic stricture was evident in the mid-portion of the CBD with proximal dilatation.\nSurgical resection of the stricture was undertaken with a Roux-en-Y hepaticojejunostomy. Since the possibility of Mycobacterial granulomas had been raised, a sample of tissue from the resected specimen was sent for mycobacterial culture.\nLiver biopsies confirmed granulomatous inflammation. Histology of the resected biliary stricture showed granulomas causing wall thickening and structuring of the bile duct. The mucosa was uninvolved (Fig. ). No malignancy was evident. Tissue sent for culture grew Mycobacterium abcessus sensitive only to Amikacin. There was no suggestion of immunodeficiency and HIV testing was negative. The patient was commenced on therapy and is currently progressing very well.