Disseminated Primary Uterine Hepatoid Adenocarcinoma with α-Fetoprotein Production Demonstrated on ¹⁸F-FDG PET/CT

We present the ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) findings in a 57-year-old woman with post-menopausal bleeding diagnosed with hepatoid adenocarcinoma (HAC) with a primary tumour in the uterine corpus and a highly elevated level of serum-α-fetoprotein (S-AFP) at presentation. HAC is a variant of adenocarcinoma with hepatic differentiation representing a heterogeneous group of neoplasms that morphologically and immunphenotypically resemble hepatocellular carcinoma (HCC) but are of extrahepatic origin. Microscopically, they are usually poorly differentiated adenocarcinomas proliferating in solid sheets or in a trabecular or cord-like arrangement. Primary uterine HAC is exceedingly rare with a general poor prognosis, and data is sparse and limited to case reports, making the clinical management challenging. Various primary anatomical sites have been reported in the literature, with the stomach being the most common primary site. ¹⁸F-FDG PET/CT plays an important role in staging and follow-up in many gynecological malignancies including uterine corpus cancer. To the best of our knowledge, this is the first report describing a primary uterine hepatoid adenocarcinoma with metastases to bone, vagina and lymph nodes on ¹⁸F-FDG PET/CT. By utilizing the ability of PET to detect early metabolic changes prior to visible structural changes on conventional imaging, this case illustrates a potential role of ¹⁸FDG-PET/CT in the staging of primary endometrial HAC by depicting distant metastasis that is not readily identifiable on CT alone.