Fumarate Hydratase-Deficient Leiomyoma with Double Mutation Sites in the FH Gene: A Rare Case Report and Literature Review.

Background: Fumarate Hydratase (FH)-deficient uterine leiomyomas are a rare type of uterine fibroid associated with somatic or germline mutations in the FH gene. Herein, we report a case of FH-deficient uterine leiomyoma with a double-site mutation of FH in a 41-year-old woman.

Case presentation: The woman was found to have an intrauterine mass during a routine physical examination two years prior. She had no previous medical history or family history of genetic diseases. Ultrasound examination revealed a slightly hypoechoic mass on the posterior wall of the uterus, approximately 4 cm × 4.1 cm in size, suggesting the possibility of a uterine fibroid. The patient opted for regular annual follow-ups and received no specific treatment. However, during the subsequent two years of follow-up, the mass was found to increase in size annually. The patient then came to our hospital and underwent laparoscopic myomectomy. Postoperative pathology indicated that the tumor was negative for FH but positive for 2-succinocysteine (2SC), suggesting a potential diagnosis of FH-deficient leiomyoma. Sanger sequencing analysis demonstrated that the leiomyoma harbored the c.724C>T (p.L242F) mutation in exon 5 and the c.1292C>T (p.T431I) mutation in exon 9 of the FH gene, further confirming the diagnosis of FH-deficient leiomyoma.

Conclusion: We report a rare case of FH-deficient uterine leiomyoma with double mutation sites in the FH gene. Pathological examination and genetic testing are crucial for a definitive diagnosis.