The endometrium is the inner layer of tissue that lines the uterus, thickening and shedding monthly in response to hormonal cycles. Its primary function is to prepare for and sustain a pregnancy. An endometrial lesion is broadly defined as an area of abnormal tissue growth or structural change within this lining. These abnormalities vary widely, ranging from common, harmless growths to precancerous changes or malignancy. Understanding these lesions requires an overview of their classification, warning signs, identification methods, and management approaches.
Classification of Endometrial Lesions
Endometrial lesions are categorized based on their cellular characteristics and potential for malignant transformation, which determines treatment urgency. The most common lesions are benign, meaning they are non-cancerous. Benign lesions include endometrial polyps, which are localized growths of endometrial tissue, and submucosal fibroids, which are benign muscle tumors protruding into the endometrial cavity.
A more concerning class of lesion is endometrial hyperplasia, involving an increased number of cells and glandular structures, leading to a thickened uterine lining. This condition is classified into two categories: Benign Endometrial Hyperplasia (BEH), often caused by prolonged estrogen exposure, which has a very low risk of progressing to cancer, and Endometrial Intraepithelial Neoplasia (EIN).
EIN, previously termed atypical hyperplasia, represents the true precancerous condition. It is characterized by architectural changes and cellular abnormalities, indicating an abnormal growth prone to becoming malignant. Patients diagnosed with EIN face a substantial risk, with concurrent invasive carcinoma found in a significant percentage of subsequent surgical specimens.
Endometrial carcinoma, or cancer, represents the malignant end of the spectrum, originating from the glandular cells. The risk of developing cancer correlates with the severity of the preceding precancerous lesion. Precise classification establishes the patient’s risk profile and determines the most appropriate course of action.
Recognizing Warning Signs
The most frequent warning sign is Abnormal Uterine Bleeding (AUB). This symptom refers to any bleeding pattern that deviates from a normal menstrual cycle. In menstruating women, AUB often manifests as heavy menstrual bleeding (menorrhagia) or irregular bleeding or spotting between expected periods.
For postmenopausal women, any vaginal bleeding or spotting is considered abnormal. Postmenopausal bleeding carries a higher potential association with precancerous lesions or malignancy and requires prompt evaluation. Other, less common symptoms include a persistent, watery, or blood-tinged vaginal discharge.
Some individuals may experience pelvic pressure or pain, especially if the lesion, such as a fibroid or a larger polyp, is present. While AUB is the earliest indicator, pain or a feeling of fullness in the pelvis are usually associated with larger, more advanced lesions or cancers that have extended beyond the uterine lining.
Methods of Diagnosis
The diagnostic process begins with investigating the abnormal bleeding or other symptoms. The initial step is often a Transvaginal Ultrasound (TVUS). TVUS measures the thickness of the endometrial lining, which can indicate the presence of a lesion or hyperplasia.
If the ultrasound reveals a thickened lining or abnormality, the next step is typically an Endometrial Biopsy, the most definitive way to determine the lesion’s nature. This procedure involves inserting a narrow, flexible tube into the uterus to suction out a small tissue sample from the lining. The sample is then sent to a pathologist to be examined under a microscope for classification.
When the office biopsy is inconclusive or a focal lesion like a polyp is suspected, a Hysteroscopy may be performed. Hysteroscopy involves inserting a thin scope through the cervix for direct visualization of the uterine cavity. This procedure can be combined with a targeted biopsy, providing a larger tissue sample for final diagnosis.
Treatment Approaches
The plan for managing an endometrial lesion correlates with the lesion’s classification, the patient’s symptoms, and their reproductive goals. For small, asymptomatic benign lesions like polyps or Benign Endometrial Hyperplasia (BEH), watchful waiting or observation may be appropriate. This involves monitoring the lesion over time with periodic check-ups and imaging.
Medical management uses hormonal therapy, specifically progestins, to treat BEH, often causing the hyperplastic tissue to regress. Hormonal therapy is also utilized for precancerous EIN patients who wish to preserve fertility, though this requires very close monitoring due to the high risk of concurrent or progressive cancer.
For symptomatic benign lesions, such as polyps causing heavy bleeding, or for confirmed precancerous lesions like EIN in patients who have completed childbearing, surgical removal is recommended. Endometrial polyps are often removed via hysteroscopic polypectomy, a minimally invasive procedure that excises the growth and preserves the uterus. Endometrial ablation, which destroys the uterine lining, is another option for benign bleeding but is not suitable for precancerous lesions.
When Endometrial Intraepithelial Neoplasia (EIN) is confirmed and the patient does not desire future children, or when any form of endometrial cancer is diagnosed, a hysterectomy is the definitive treatment. This surgery involves the removal of the uterus, often accompanied by the removal of the fallopian tubes and ovaries in cases of cancer. The extent of the surgery is determined by the lesion’s severity and the risk of spread.