Benign Tumours of the Endometrium

Benign tumours of the endometrium are an overarching category encompassing endometrial polyps and endometrial hyperplasia. Endometrial polyps are the commonest specific benign endometrial tumour. Endometrial hyperplasia is a proliferative endometrial abnormality reflecting excessive, unopposed oestrogen stimulation. Each is an important, common cause of abnormal uterine bleeding.

Careful diagnostic evaluation is essential given the substantial symptomatic burden these conditions can produce. It is particularly relevant to endometrial hyperplasia, given the recognised potential for a subset of specific histological patterns to progress toward endometrial malignancy if left inadequately identified and treated.

Classification and pathophysiology

• Endometrial polyps reflect localised, benign overgrowth of endometrial glands and stroma, typically projecting into the endometrial cavity on a stalk.
• The underlying cause is incompletely understood. It is believed to reflect a combination of localised hormonal sensitivity and, in some cases, association with tamoxifen use. This reflects the specific, partial oestrogen agonist effect of tamoxifen on endometrial tissue despite its predominantly antagonist effect within breast tissue.
• Endometrial hyperplasia reflects excessive endometrial glandular proliferation resulting from sustained, unopposed oestrogen exposure without the counterbalancing effect of adequate, regular progestogen exposure.
• It is classified according to the presence or absence of cytological atypia. This is a critical, essential distinction. Hyperplasia without atypia carries a relatively low progression risk to endometrial cancer.
• Atypical hyperplasia carries a substantially elevated progression risk. It frequently coexists with an already established, though not yet identified, concurrent endometrial malignancy at the time of diagnosis.
• Relevant risk factors for endometrial hyperplasia mirror those relevant to unopposed oestrogen exposure more broadly, including obesity, polycystic ovary syndrome and associated chronic anovulation, unopposed oestrogen therapy, and tamoxifen use.

• Abnormal uterine bleeding is the characteristic presenting feature for both endometrial polyps and endometrial hyperplasia. It includes intermenstrual bleeding, heavy menstrual bleeding, or, particularly relevant and always warranting prompt evaluation, postmenopausal bleeding.
• Endometrial polyps may occasionally be entirely asymptomatic, identified incidentally on pelvic ultrasound performed for an unrelated indication.
• Polyps may also present with intermenstrual spotting or postcoital bleeding, where the polyp surface is friable or prolapses through the cervical canal.
• Endometrial hyperplasia typically presents with a pattern of irregular, sometimes heavy uterine bleeding. This often occurs in the context of chronic anovulation, relevant to the underlying unopposed oestrogen exposure driving the condition.
• It is correspondingly frequently associated with a history of irregular menstrual cycles preceding the onset of the abnormal bleeding pattern.
• Postmenopausal bleeding carries a direct need to exclude endometrial malignancy. Any postmenopausal woman presenting with bleeding requires prompt, full evaluation, whether it is attributable to a benign polyp, hyperplasia, or another cause. Do not assume a benign cause without appropriate investigation.

• Transvaginal ultrasound is the standard initial imaging investigation. Endometrial polyps are typically visualised as a discrete, echogenic endometrial lesion. Endometrial hyperplasia typically produces generalised endometrial thickening.
• The specific endometrial thickness measurement carries particular relevance to risk assessment in postmenopausal women.
• Saline infusion sonohysterography involves instillation of saline into the endometrial cavity during ultrasound assessment to improve visualisation of the endometrial contour. It provides valuable, enhanced characterisation, particularly relevant to confirming and precisely localising a suspected endometrial polyp.
• Hysteroscopy, with directed biopsy of any visualised abnormality, is the definitive diagnostic approach and, for polyps specifically, simultaneously therapeutic.
• It allows direct visualisation of the endometrial cavity together with full, targeted tissue sampling. This is essential for accurate histological diagnosis and, critically, exclusion of any coexisting atypia or malignancy.
• Endometrial biopsy, whether obtained via outpatient pipelle sampling or through formal hysteroscopic-directed biopsy, provides essential histological characterisation.
• Hysteroscopic-directed sampling is generally preferred where a discrete, focal abnormality such as a polyp is identified. Blind, outpatient sampling techniques are limited in reliably capturing focal, rather than diffuse, endometrial pathology.

• Endometrial polyps causing symptomatic bleeding, or identified in a postmenopausal woman, are managed with hysteroscopic polypectomy. This provides both symptomatic resolution and definitive histological characterisation.
• In a postmenopausal woman the threshold for removal and histological confirmation is generally lower, given the relevant, though still low, associated malignancy risk in this population.
• Asymptomatic endometrial polyps in a premenopausal woman may be managed with either surveillance or removal, according to individual clinical circumstances, patient preference, and any relevant additional risk factors.
• Endometrial hyperplasia without atypia is generally managed with progestogen therapy. Options are the levonorgestrel-releasing intrauterine system, a particularly effective approach given direct, sustained local endometrial progestogen delivery, or oral progestogen therapy.
• Follow-up endometrial biopsy is structured to confirm histological regression. This reflects the generally favourable response and relatively low associated malignancy progression risk characteristic of this histological category.
• Atypical endometrial hyperplasia warrants more definitive management, given the substantial associated risk of progression to, or coexistence with, endometrial malignancy. Hysterectomy is generally recommended for women who have completed childbearing.
• Carefully selected, appropriately counselled women wishing to preserve fertility may be managed with high-dose progestogen therapy and very close, structured surveillance. Deliver this through specialist gynaecological oncology involvement, given the substantial, relevant malignancy risk associated with this histological finding.
• Management of any identifiable underlying contributing cause is an important, complementary component of full management. It addresses the underlying hormonal imbalance alongside direct treatment of the endometrial abnormality itself.
• Examples are weight management where obesity is a relevant factor, and appropriate management of chronic anovulation where polycystic ovary syndrome is the relevant underlying context.
• Full, structured follow-up and surveillance, together with clear patient education regarding the specific diagnosis and its implications, underpins appropriately risk-stratified management of this important category of benign endometrial pathology.
• Atypical hyperplasia specifically requires particularly careful and definitive management.