Endometrial hyperplasia

Endometrial hyperplasia refers to an increasedis abnormal proliferation of the endometrial glands relative to theand stroma, defined as diffuse smooth thickening > 10 mm. One¹³ 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 smooth increase in endometrial thickness, but endometrial hyperplasia may also cause asymmetric/focal thickening with surface irregularity, an appearance that is suspicious for carcinoma. Cystic changes can also be seen in endometrial hyperplasia.

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