Hepatocellular adenoma and focal nodular hyperplasia after long-term use of danazol for endometriosis: a case report.

Danazol, an inhibitor of pituitary gonadotropin with weak androgenic effect, is currently being used for the treatment of endometriosis. In contrast to other C17 alkylated anabolic steroids, it has been rarely associated with the occurrence of primary liver tumors. We present the case of a patient with endometriosis in whom a hepatocellular adenoma was discovered after 14 years of treatment with danazol for endometriosis. The patient showed no clinical signs of a liver tumor and it was only detected by ultrasonography and magnetic resonance imaging (MRI). When long-term danazol therapy is required, regular ultrasonography for monitoring and early tumor detection is recommended.