Masquerading as Malignancy: A Case of a Misleading Gallbladder Abscess

Abstract

Introduction: A gallbladder mass should always concern a clinician for malignancy. However, clinical and radiologic data are surprisingly similar for benign and malignant disease. A few cases of gallbladder abscesses mimicking cancer have been described in the setting of cholecystitis or as a complication of spilled gallstones after laparoscopic cholecystectomy. Our case is unique, as our patient had no known risk factors for abscess formation. Case: A 64-year old male presented with intermittent abdominal pain and fevers, night sweats, and 30-pound weight loss over 2 months. Physical exam was unremarkable. Lab studies showed mild leukocytosis with WBC 13.6 and normal LFTs. CT scan revealed a gallbladder mass with pneumobilia. MRI showed a diffusely thickened gallbladder with fistulization to the transverse colon, suspicious for malignancy. CA-19-9 was normal. PET-CT depicted increased uptake in the area of the gallbladder and hepatic flexure. Pre-operative diagnosis of gallbladder cancer was made and a radical en bloc cholecystectomy with partial hepatectomy and partial transverse colectomy was performed. Post-operative pathology revealed no malignancy, but rather an abscess involving the liver, gallbladder, and colon. Discussion: Diagnosis of gallbladder pathology is challenging due to nonspecific clinical and radiologic findings. The four distinct radiologic patterns are polypoid gallbladder mass, focal or diffuse gallbladder wall thickening, polypoid bile duct mass, and focal bile duct stricture. These can occur with benign or malignant lesions. Specificity of US, CT and MRI to distinguish benign from malignant gallbladder lesions is poor. Additionally, PET yields false positives in inflammation. Known masqueraders in the gallbladder are adenomyomatosis, xanthogranulomatous cholecystitis, and tuberculoid granulomatosis. Our patient had an intact gallbladder with no signs of cholelithiasis, cholecystitis, or other chronic process. Further review of his case revealed hepatic flexure diverticula on CT and foreign body giant cells in the abscess on pathology suggesting a possible perforated diverticulitis with fistulization to the gallbladder as the etiology of our patient's abscess. The best means of accurately diagnosing gallbladder pathology remains to be determined. Clinicians must beware of radiologic limitations and hold a high index of suspicion for malignancy in the right clinical context, but be mindful of mimicry as well.Figure 1Figure 2