What Causes Endometrial Thickening?

Endometrial thickening, also known as endometrial hyperplasia, carries a certain risk of malignant transformation and is therefore classified as a precancerous condition. However, long-term clinical observation indicates that the majority of endometrial hyperplasia cases are reversible or remain in a stable, benign state. Only a small proportion of patients may progress to endometrial cancer after an extended period. So, what causes endometrial thickening? The following section addresses this question.

Causes of Endometrial Thickening

1. Gynecological Disorders

Endometrial thickening is often associated with gynecological conditions such as ovarian cysts, uterine fibroids, and endometriosis. Due to the anatomical interconnectivity of the female reproductive system, pathology in one area may affect other regions. Therefore, women should monitor their bodies closely and seek timely medical evaluation and treatment to prevent endometrial thickening.

2. Endocrine-Functional Tumors

Endometrial thickening may result from endocrine-functional tumors—rare neoplasms accounting for approximately 10% of cases. Abnormal gonadotropin secretion by the pituitary gland, for instance, can lead to persistent estrogen production by ovarian granulosa cell tumors. Additionally, complex endometrial hyperplasia may also contribute to endometrial thickening.

3. Simple Endometrial Hyperplasia

Simple endometrial hyperplasia is another common cause of endometrial thickening. When the affected uterus is slightly enlarged, the endometrium may exhibit marked thickening, sometimes presenting as diffuse polypoid changes. Large curettage specimens may contain smooth, red, polypoid tissue. Microscopically, lesions typically appear diffuse and may involve both the functional and basal layers of the endometrium.

The above outlines the primary causes of endometrial thickening. Furthermore, obesity may also contribute to endometrial thickening. Excess adipose tissue promotes the conversion of adrenal-derived androstenedione into estrone, thereby stimulating endometrial proliferation and thickening.