A case of clear cell-hepatocellular carcinoma accidentally found in the gallbladder wall after laparoscopic resection of gallbladder empyema: Beware of the liver bed

INTRODUCTION AND IMPORTANCE: Hepatocellular carcinoma (HCC) invading the gallbladder is a rare scenario, even in the context of an advanced tumor. The clear cell variant of HCC (CC-HCC) is also rare. However, CC-HCC is more frequent in women and those with liver cirrhosis, and the standard definition is the presence of transparent cytoplasm in at least 50 % of tumor cells. CASE PRESENTATION: An accidental finding of HCC was made during histological examination of a gallbladder empyema specimen from a 74 year-old male patient. The tumor was found to be invading the wall of the gallbladder. On post-operative imaging, the HCC was identified in liver segments 4b, 5 and 6, with extensive portal vein thrombosis; without other distant spread. The tumor in our case was almost exclusively comprised of clear cells (>90 %); therefore, it was classified as CC-HCC. CLINICAL DISCUSSION: Tumors are rarely discovered along with acute cholecystitis. Furthermore, HCC rarely invades the wall of the gallbladder. HCC with clear cell histology should be distinguished from other regional and metastatic tumors of similar morphology. CONCLUSION: In this particular case, we provide an unusual circumstance in which HCC invaded the gallbladder wall and was found by chance in a specimen obtained after a cholecystectomy. Malignancy remains an under-recognized clinical scenario that is easily overlooked when assessing patients presenting with cholecystitis. We report our case with an additional focus on the findings of computed tomography (CT) as well as the clinicopathological characteristics pertinent to this distinctive histologic pattern of CC-HCC.