Myomatous erythrocytosis syndrome associated with an 8-kg uterine leiomyoma: a case report of diagnostic evaluation and perioperative management.

Myomatous erythrocytosis syndrome (MES) is a rare condition in which erythrocytosis associated with uterine leiomyoma resolves after tumor removal. A 55-year-old woman with a giant uterine mass that had continued to enlarge despite long-term leuprorelin treatment was referred for marked erythrocytosis. Treatment-related amenorrhea made the timing of natural menopause uncertain. Magnetic resonance imaging showed a heterogeneous uterine mass exceeding 30 cm. Hemoglobin was 20.1 g/dL and serum erythropoietin (EPO) was 45.4 mIU/mL. BCR-ABL1 testing was negative, and no JAK2 V617F, JAK2 exon 12, CALR, or MPL mutation was detected, supporting secondary rather than clonal erythrocytosis. Ten weekly therapeutic phlebotomies reduced hemoglobin to 15.8 g/dL. Total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed after multidisciplinary perioperative planning. Prominent omental collateral vessels and markedly dilated ovarian veins increased surgical complexity. Because the giant tumor restricted posterior pelvic access, hysterectomy was completed using a retrograde approach. The 8060-g specimen was histologically confirmed as a benign uterine leiomyoma, and superficial cystic structures were identified as D2-40-positive dilated lymphatic channels. No thrombotic event occurred. At one-month follow-up, hemoglobin and serum EPO had decreased to 11.4 g/dL and 16.0 mIU/mL, respectively, without recurrent erythrocytosis. Although tumor EPO expression was not evaluated, postoperative normalization of serum EPO and resolution of erythrocytosis supported the clinical diagnosis of MES. MES should be considered in patients with uterine leiomyoma and unexplained erythrocytosis; hematologic evaluation, preoperative phlebotomy, and multidisciplinary surgical planning may enable safe treatment.