AMH and Kisspeptin Receptor Expression in Rare Hydropic Leiomyoma: A Case Study.

BACKGROUND Leiomyomas are common benign uterine tumors (BUMTs) with diverse histopathological subtypes and variable clinical presentations. While most are asymptomatic, some cause significant morbidity, including abnormal uterine bleeding, infertility, and pain. Hydropic leiomyomas (HLMs) are rare variants histopathologically characterized by zonal edema and may pose diagnostic challenges, particularly when located in atypical sites such as the retroperitoneal space. This report presents a case of a retroperitoneal HLM with strong expression of anti-Müllerian hormone (AMH) and its receptor (AMHR2), and kisspeptin (KISS1) and its receptor (KISS1R), suggesting potential new therapeutic targets. CASE REPORT A 44-year-old woman presented with acute lower abdominal pain. Magnetic resonance imaging (MRI) revealed a well-circumscribed, pedunculated retroperitoneal mass originating posteriorly from the uterine body-cervix junction. MRI findings suggested a benign mesenchymal tumor but could not exclude malignancy. Surgical excision was performed, and histopathological examination confirmed HLM. Immunohistochemical analysis demonstrated strong nuclear and cytoplasmic expression of AMH, AMHR2, KISS1, and KISS1R in tumor cells, making this the first reported case of such expression in HLM. The patient had an uneventful postoperative course, and no recurrence was observed during a 2-year follow-up. CONCLUSIONS This case underscores the diagnostic complexity of retroperitoneal HLMs and the importance of MRI in differentiating BUMTs from malignancies. Strong AMH, AMHR2, KISS1, and KISS1R expression suggests a potential role of these regulatory proteins in HLM pathophysiology. Further research on targeted modulation of these pathways may provide novel therapeutic approaches for BUMTs, particularly in cases where conventional treatments are limited.