Melatonin Receptors in Uterine Leiomyomas: An Immunohistochemical Study

Uterine leiomyomas are the most common benign tumors in women of reproductive age, often causing significant symptoms such as abnormal bleeding, pain, and infertility. Melatonin, a hormone with anti-proliferative and oncostatic properties, has been studied; however, its effects on uterine leiomyomas remain unclear.

This study aimed to evaluate the immunohistochemical expression of melatonin receptors MT1 and MT2 in uterine leiomyomas compared to normal myometrium, and to correlate their expression with clinical and histopathological features.

A case-control study was conducted on ninety cases retrieved (60 leiomyoma cases, thirty normal myometrium controls). Immunohistochemical staining was performed to assess the expression of MT1 and MT2 receptors. Clinical data were collected, and statistical analyses were conducted to evaluate associations between receptor expression and demographic, clinical, and histological features.

MT1 and MT2 were significantly overexpressed in leiomyomas compared to controls (MT1: 70% vs. 30%, p < 0.0001; MT2: 60% vs. 16.7%, p < 0.0001). A strong positive correlation was observed between MT1 and MT2 expression (r = 0.6, p < 0.0001). MT1 score varied significantly with age (p = 0.03), tumor location (p = 0.04), and presenting symptoms (p = 0.03), while MT2 expression was positively associated with the number of lesions (p = 0.033).

Melatonin receptors MT1 and MT2 are significantly upregulated in uterine leiomyomas, suggesting a potential role in their pathogenesis. These findings support further investigation into melatonin-based therapies as adjunctive treatments for leiomyomas.