Abstract / Summary
Abstract Background Epithelioid uterine leiomyoma is an uncommon histological variant and is exceptionally rare in adolescence. Its unusual anatomical presentation may complicate preoperative characterization, while definitive diagnosis relies on histopathological evaluation, including distinction from other uterine smooth muscle tumors such as smooth muscle tumors of uncertain malignant potential (STUMP). Case presentation A 15-year-old adolescent presented with progressive dysmenorrhea and pelvic pain. Transabdominal ultrasound and pelvic magnetic resonance imaging revealed a solid infraligamentary uterine mass with imaging features predominantly suggestive of a benign leiomyoma. Given the persistence of symptoms, fertility-preserving laparoscopic myomectomy was performed. Histopathological and immunohistochemical examination demonstrated an epithelioid leiomyoma characterized by mild-to-moderate cytological atypia, very low mitotic activity (generally < 2 mitoses/10 high-power fields, with a maximum count of 2/10 HPF), absence of tumor necrosis, and a low proliferative index. Expert pathological review supported the diagnosis of epithelioid leiomyoma, while noting features close to the diagnostic boundary with STUMP and recommending close follow-up. At three-month short-term follow-up, the patient was asymptomatic, with no clinical or imaging evidence of recurrence; however, this interval is insufficient to assess long-term biological behavior or recurrence risk. Clinical relevance This case highlights the diagnostic value of imaging–pathology correlation in an adolescent with an uncommon infraligamentary epithelioid uterine leiomyoma. Accurate histopathological characterization, including distinction from STUMP and other smooth muscle tumors, supports appropriate fertility-preserving management and informs individualized follow-up. Conclusion Epithelioid uterine leiomyoma should be considered in the differential diagnosis of pelvic masses in adolescents, particularly when arising in an unusual anatomical location. Imaging–pathology correlation is essential for accurate characterization, while histopathological assessment provides definitive tumor classification. In this patient, fertility-preserving laparoscopic myomectomy was feasible and allowed complete lesion excision while preserving the uterus; this single case does not establish comparative effectiveness or long-term outcomes.