Metastases to the gallbladder: Challenges of clinical and frozen section diagnosis.

Gallbladder metastases are rare and the clinical presentations are often nonspecific. Intra-operative gross and frozen section diagnosis can be particularly challenging. Here we present three cases and reviewed the patients' clinical, gross, frozen, and final pathology findings. Patient one is a 59-year-old male with a history of clear cell renal cell carcinoma status post partial nephrectomy seven years ago. Surveillance imaging showed two small gallbladder polyps. Intra-operative gross examination showed gallbladder with a firm, polypoid area and two detached nodules. Frozen sections of the polypoid area showed histiocytic appearing inflammation and was interpreted as chronic cholecystitis. Permanent sections showed similar morphology, but positive pancytokeratin and PAX8 immunostaining confirmed metastatic renal cell carcinoma. Interestingly, sections of the detached nodules showed better tumor morphology. Patient two is an 81-year-old male with a history of urothelial carcinoma status post transurethral resection two years ago. He presented with right upper quadrant pain, and imaging showed emphysematous cholecystitis. The gallbladder was unremarkable grossly; however, histologic sections showed metastatic urothelial carcinoma. Patient three is a 55-year-old female with a history of metastatic melanoma three years ago. PET/CT showed a stable FDG-avid gallbladder lesion. Grossly the gallbladder wall showed pigmented areas and histologic sections showed metastatic melanoma. Our study shows that the clinical, gross, and frozen section diagnosis of gallbladder metastases can be challenging. Avoiding a diagnostic error will likely entail an integrated approach, inclusive of a thorough review of clinical history, a detailed gross inspection and adequate tissue sampling.