18F-FDG PET/CT of Primary Mediastinal Hepatoid Adenocarcinoma

Metastatic mediastinal hepatoid adenocarcinoma

Hepatoid adenocarcinoma (HAC) of the mediastinum is a rare extrahepatic tumour that pathologically and morphologically resembles hepatocellular carcinoma. Extrahepatic HACs primarily occur in the stomach, ovaries, lung, gallbladder, pancreas and uterus. Patients with mediastinal HAC tend to be male smokers over forty years of age. Clinical symptoms of HAC are non-specific and varied in nature; therefore, diagnosis can be challenging and often delayed. Diagnostic investigations encompass haematological, radiological and histological assessment. Surgical resection is reserved for early-stage patients; however, since diagnosis may be delayed, most patients present with metastatic disease, for which the treatment of choice is platinum-based chemotherapy.

FDG PET/CT of Hepatoid Adenocarcinoma of the Gallbladder

Primary hepatoid adenocarcinoma of the gallbladder is rare. A 67-year-old woman presented with right upper quadrant abdominal pain with elevated α-fetoprotein level. Abdominal ultrasound and MRI showed a tumor in the gallbladder with normal liver. FDG PET/CT showed increased FDG uptake of the gallbladder tumor with retroperitoneal lymph node metastasis. Cholecystectomy was performed. Primary hepatoid adenocarcinoma of the gallbladder was confirmed by histopathology.