Immunohistochemical and molecular analysis of an α-fetoprotein-producing cervical adenocarcinoma with clear cell morphology

Adenocarcinomas with clear cell morphology may be associated with elevated serum alpha-fetoprotein levels in various organs. We report the case of an alpha-fetoprotein-producing cervical adenocarcinoma with clear cell morphology and compare it immunohistochemically, molecularly, and virologically with cervical clear cell carcinoma, gastric-type mucinous carcinoma, and ovarian clear cell carcinoma. A 51-year-old Japanese woman was initially diagnosed with cervical clear cell carcinoma. The tumor was resistant to standard surgery, radiotherapy, and chemotherapy. Serum carcinoembryonic antigen and alpha-fetoprotein were elevated. The tumor was immunohistochemically positive for alpha-fetoprotein, human chorionic gonadotropin, cytokeratin 20, spalt-like transcription factor 4, glypican 3, MUC6, and HIK1083. Gene panel testing revealed CCNE1 amplification, CDKN2A loss, and TP53 R282W. We compared the present case with 120 ovarian clear cell carcinoma cases using a tissue microarray. Only one case (0.8%) showed very limited immunohistochemical positivity for alpha-fetoprotein. Of the 54 cases in which serum carcinoembryonic antigen was measured, only one (1.9%) was elevated (19.9 ng/mL). We diagnosed the case as alpha-fetoprotein-producing cervical gastric-type mucinous carcinoma with enteroblastic differentiation. In conclusion, alpha-fetoprotein-producing cervical adenocarcinoma is a rare but aggressive tumor. Clinicians and pathologists should be aware of this unfamiliar tumor, its diagnostic clues, prognostic markers, and treatment strategies.