Primary Hepatic Acinar Cell Carcinoma
Supervisor / Principle Investigator:
MD Class of 2019
A large mass identified as primary hepatic acinar cell carcinoma (ACC) was incidentally diagnosed in a clinically asymptomatic 80-year-old man. Gadolinium-enhanced magnetic resonance imaging (MRI) revealed a heterogenous, cystic 7.7 x 11.1 x 10.4 cm tumour occupying hepatic segments II and III that was not present on abdominal ultrasound 16 months prior. The mass demonstrated mild diffuse enhancement in hepatic arterial phase with minimal portal venous washout in a liver without cirrhotic features. A central stellate necrotic scar and outer capsule were also apparent. The predominant differential diagnosis included fibrolamellar hepatocellular carcinoma (HCC) or cholangiocarcinoma. The patient underwent a formal left hepatic lobectomy and tolerated the procedure well. The tumour immunophenotype was atypical for the presumptive diagnoses and required extensive morphologic workup by electron microscopy (EM). Acinar cell differentiation was best observed on EM that included the presence of zymogen-like granules. This in conjunction with cells expressing PAS-positive diastase-resistant granular cytoplasmic contents and intracytoplasmic microvilli, was then primary hepatic ACC definitively diagnosed. The patient had a follow-up positron emission tomography (PET) scan X months later which corroborated no distant disease or local recurrence. A review of five previous case reports of ACC originating from the liver were compiled and summarized in this study. Hepatic ACC may be confused with other malignant or benign hepatic masses based on nonspecific imaging patterns. This may have previously led to poor patient outcomes due to misdiagnosis. The aim of this study is to further characterize a rare malignant tumour emanating from a unique location.