Endometrial hyperplasia

Endometrial hyperplasia refers to an increased proliferation of the endometrial glands relative to the stroma. One of the main concerns is the potential malignant transformation of the endometrial hyperplasia to the endometrial carcinoma.

Epidemiology

Endometrial hyperplasia affects women of all age groups ¹².

Clinical presentation

A great majority of patients present with abnormal uterine bleeding. 

Pathology

Hyperplasia with increased gland to stroma ratio; there is a spectrum of endometrial changes ranging from glandular atypia to frank neoplasia.

There are several types of endometrial hyperplasia, which include:

• simple hyperplasia without atypiaalso known as cystic endometrial hyperplasia
• simple hyperplasia with atypia 
• complex hyperplasia without atypia 
• complex hyperplasia with atypia 

Hyperplasia can be also classified into two broad groups ⁵:

• hyperplasia without cellular atypia
• hyperplasia with cellular atypia

Associations

Unopposed oestrogen stimulation (either from an endogenous or exogenous source) is implicated in its pathogenesis; some of these conditions are:

• obesity
• polycystic ovary syndrome
• pregnancy (and ectopic pregnancy)
• oestrogen secreting ovarian tumours
  • granulosa cell tumour of the ovary
• tamoxifen 

Radiographic features

Ultrasound

Imaging the endometrium on days 5-10 of a woman's cycle reduces the variability in endometrial thickness.

• premenopausal
  • normal endometrial thickness depends on the stage of the menstrual cycle, but a thickness of >15 mm is considered top normal in the secretory phase
  • hyperplasia can be reliably excluded in patients only when the endometrium measures less than 6 mm ¹
• postmenopausal
  • a thickness of >5 mm is considered abnormal

The appearance can be non-specific and cannot reliably allow differentiation between hyperplasia and carcinoma ⁵. Usually, there is a homogeneous increase in endometrial thickness, but endometrial hyperplasia may also cause asymmetric/focal thickening with surface irregularity, an appearance that is suspicious for carcinoma.

Pelvic MRI

• T2: hyperplasia is often isointense to hypointense to normal endometrium ⁷

Treatment and prognosis

Up to one-third of endometrial carcinoma is believed to be preceded by hyperplasia. A biopsy is required for a definitive diagnosis.

Because endometrial hyperplasia has a non-specific appearance, any focal abnormality should lead to biopsy if there is clinical suspicion for malignancy (e.g. vaginal bleeding).

Differential diagnosis

On ultrasound, appearances can potentially simulate:

• normal thickening during the secretory phase: see endometrial thickness
• sessile endometrial polyp(s): may contain cystic spaces ⁴
• submucosal uterine fibroids
• endometrial cancer
• adherent intrauterine blood clot
• pregnancy (and ectopic pregnancy)

See also

• abnormal thickening of the endometrium