A Case of Familial Mediterranean Fever Diagnosed After Oral Administration of a Gonadotropin-Releasing Hormone (GnRH) Antagonist.

Familial Mediterranean fever (FMF) is a juvenile-onset autoinflammatory disease involving recurrent peritonitis. Although the pathogenesis of the disease remains unclear, FMF is caused by dysfunction of the pyrin protein, which suppresses the activity of the inflammasome, a component of the inflammatory pathway, and various factors have been identified. In particular, the high frequency of female patients suggests an association with the menstrual cycle. We describe a case of peritonitis that developed in association with menstruation but was initially treated as a gynecological symptom due to the presence of uterine fibroids. The diagnosis of FMF was made after the use of gonadotropin-releasing hormone (GnRH) antagonists to eliminate the association with menstruation. This case emphasizes the potential for initial misdiagnosis due to the presence of an organic disease, particularly in FMF, and highlights the importance of considering both clinical findings and the disease course.