[Clinicopathological features and prognosis of 117 cases of fumarate hydratase-deficient uterine leiomyomas].

Objective: To explore the clinicopathological characteristics and prognosis of fumarate hydratase-deficient uterine leiomyoma (FH-dUL). Methods: Clinical data and follow-up information for 117 patients with FH-dUL diagnosed through surgical pathology and immunohistochemistry in the First Affiliated Hospital of Nanjing Medical University from January 2020 to December 2024, were collected. A control group of 130 patients with common uterine leiomyomas was also included. The differences between the two groups in clinical, imaging, and pathological characteristics were compared. Additionally, recurrence rates, fertility outcomes for FH-dUL patients, and the incidence of renal cancer in FH germline mutation carriers were monitored. Results: (1) Comparison of clinicopathological characteristics: the median age of 117 FH-dUL patients was 35 years, and the median age at first diagnosis of uterine leiomyomas was 29 years, both significantly younger than the control group (41 and 36 years; both P<0.01). The FH-dUL group showed significantly higher incidences of uterine myomectomy, multiple leiomyomas, diffusion restriction on pelvic magnetic resonance imaging diffusion weighted imaging, and typical pathological features (candelabra-like vessels, bizarre nuclei, cytoplasmic eosinophilic globules, perinuclear halo, cellular atypia) and higher ultrasound blood flow score (all P<0.05). Of the 30 FH-dUL patients who underwent genetic testing, 9 had germline mutations, 3 had somatic mutations, and 6 had mutations of unclear origin. Among the 9 FH gene germline mutation patients, 2 had already developed renal cell carcinoma. (2) Recurrence analysis: among the 56 patients who underwent uterine myomectomy, 22 (39.3%, 22/56) experienced recurrence during follow-up, compared to 12 (21.8%, 12/55) of the 55 patients in the control group, the difference between the two groups was statistically significant (P=0.046). Multivariate binary logistic regression analysis showed that cellular leiomyomas (OR=9.489, 95%CI: 1.740-51.755; P=0.009) and multiple uterine leiomyomas (OR=10.709, 95%CI: 1.354-84.683; P=0.025) were significant risk factors for recurrence in FH-dUL. (3) Fertility analysis: among the 66 FH-dUL patients who underwent fertility-preserving surgery, 16 had the intention to have fertility desire, only 2 (2/16) completed their fertility plans during follow-up. Conclusions: Clinicopathological features and imaging features help to differentiate FH-dUL from common type uterine fibroids, but lack specificity, and the diagnosis of FH-dUL is based on immunohistochemistry. The recurrence rate after resection of FH-dUL is high, and cellular and multiple leiomyomas are important predictors of recurrence. It is crucial to perform genetic testing, genetic counseling, drug treatment to prevent recurrence, fertility guidance, and long-term comprehensive management after surgery for FH-dUL management.