A case of hereditary persistence of α-fetoprotein: diagnostic usefulness of the subfraction profile.

α-Fetoprotein is a well-established tumor marker for non-seminomatous germ cell tumors. Elevated α-fetoprotein levels, however, result from a variety of clinical conditions. Hereditary persistence of α-fetoprotein is a rare benign disorder in which serum α-fetoprotein levels are persistently elevated, but there are no disabilities and symptoms. A 35-year-old man was diagnosed with pT1 testicular embryonal carcinoma. Post-orchiectomy α-fetoprotein levels remained persistently elevated without clinical or radiographic abnormalities. His mother's elevated α-fetoprotein levels confirmed the diagnosis of hereditary persistence of α-fetoprotein. Lens culinaris agglutinin-reactive α-fetoprotein fractions have been reported as a useful diagnostic marker for non-seminomatous germ cell tumors; in this patient, its measurement showed high non-reactive α-fetoprotein levels, which indicated the low probability of residual tumors. The present case represents the third case of hereditary persistence of α-fetoprotein in Japan, and the first in which the α-fetoprotein subfraction was evaluated.