Description
Adenomyosis is a common benign condition characterised by the ectopic presence of endometrial glands and stroma within the myometrium of the uterus. This disorder is part of a spectrum of disorders linked with the mislocalisation of endometrial tissues, such as endometriosis. Adenomyosis can be further classified into diffused and focal (adenomyoma) forms, with the latter sometimes leading to the development of cystic adenomyosis.
Pathogenesis
The pathogenesis of adenomyosis remains under investigation, but it is believed to involve invagination of the endometrial basalis layer into the myometrium, stimulated by the local production of oestrogen and progesterone. The endometrial tissue responds to hormonal stimuli, causing it to proliferate and shed during each menstrual cycle.
Subtypes
- Diffuse adenomyosis: The most common form, characterised by widespread involvement of the myometrium.
- Focal adenomyosis (adenomyoma): Presents as a localised mass within the myometrium.
- Cystic adenomyosis: Rare form of adenomyoma characterised by large cystic spaces filled with haemorrhagic or serous fluid.
Epidemiology, Risk Factors & Associations
- Adenomyosis is common in women in their 40s and 50s and is associated with parity.
- Factors associated with adenomyosis include multiparity, prior uterine surgery, and oestrogen exposure.
- Association with endometriosis and fibroids is well documented.
Clinical Features
- Adenomyosis often presents with menorrhagia, dysmenorrhoea, and chronic pelvic pain.
- In some women, it may be asymptomatic and discovered incidentally during imaging or surgery for other gynaecological conditions.
Complications
- Adenomyosis can cause significant morbidity due to pain and heavy menstrual bleeding.
- It may contribute to infertility and adverse pregnancy outcomes.
Pathological Features
Histopathology
- Macroscopic: In diffuse adenomyosis, the uterus is often enlarged and bulky. In focal adenomyosis, a well-defined mass may be seen within the myometrium.
- Microscopic: Histologically, it is characterised by endometrial glands and stroma surrounded by hypertrophic and hyperplastic myometrium.
Radiological Features
General Features
- Adenomyosis is typically characterised by diffuse or focal thickening of the junctional zone on imaging.
- The presence of tiny cysts within the thickened junctional zone is a characteristic feature.
- Focal adenomyosis or adenomyoma appears as a well-defined mass within the myometrium, often with a heterogeneous signal on MRI due to haemorrhage and degeneration. They tend to be contiguous with the junctional zone. Internal foci of T1 and T2 hyperintensity correspond to haemorrhagic endometrial glands
Ultrasound
- On ultrasound, adenomyosis often presents as a heterogeneous or diffusely enlarged uterus. Myometrial cysts may also be identified.
CT
- Non-contrast: On non-contrast CT, adenomyosis may be difficult to detect but can present as a diffusely enlarged uterus.
- Contrast-enhanced: The contrast-enhanced phase may show heterogeneous enhancement in the myometrium.
MRI
- T1: Adenomyosis often presents with low signal intensity.
- T2: The junctional zone is thickened and appears high in signal intensity.
- T1 C+: After gadolinium contrast administration, adenomyosis enhances homogeneously in diffuse cases and heterogeneously in focal adenomyosis or adenomyoma.
Diagnosis
The diagnosis of adenomyosis is often suggested by clinical findings and imaging but can only be definitively confirmed by histopathological examination, typically after hysterectomy.
Differential Diagnosis
- Leiomyoma: Common uterine tumour, usually well-defined, markedly T2 hypointense, and may contain calcifications.
- Endometrial carcinoma: Arises from the endometrium and has a completely different clinical and imaging presentation.
Management
The management of adenomyosis depends on the severity of symptoms and the patient’s reproductive plans. Medical management with hormonal therapy, such as oral contraceptives or progesterone IUD, is often the first-line treatment. Surgical management, including endometrial ablation, uterine artery embolisation, and hysterectomy, may be indicated for women with severe symptoms unresponsive to medical therapy or for those who have completed childbearing.