CASE 18517 Published on 08.04.2024

External adenomyosis


Genital (female) imaging

Case Type

Clinical Case


Diogo Costa Carvalho, Eduardo Negrão, Ana Teresa Vilares

Department of Radiology, University Hospital Center of São João, Porto, Portugal


47 years, female

Area of Interest Pelvis ; Imaging Technique MR
Clinical History

A 47-year-old woman with a previous right salpingo-oophorectomy due to a large endometrioma was seen in a gynaecology consult, with complaints of amenorrhea. She denied menometrorrhagia, dysmenorrhea or dyspareunia. A transvaginal ultrasound (TVUS) demonstrated a heterogeneous myometrium, and a pelvic magnetic resonance imaging (MRI) examination was performed.

Imaging Findings

MRI was performed on a 3-Tesla magnet using a protocol with T2-weighted images (T2WI), T1-weighted images (T1WI), diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC).

Fibrotic changes compatible with deep infiltrating endometriosis (DIE) were seen centred in the uterine torus, with a conspicuous plaque of DIE extending posteriorly to the sigmoid colon, where transmural invasion was seen (Figures 1a, 1b and 1c). This plaque also extended anteriorly, embracing and altering the posterior uterine contour, infiltrating the posterior myometrium of the uterine body, which presented a mass-like bulky appearance, mildly hypointense on T2WI, compatible with solid invasive endometriosis, or external adenomyosis. Small hyperintense foci on T2WI were also depicted within this lesion, compatible with small intra-myometrial cysts, some of them hyperintense on T1WI (Figures 1a, 1b, 1c and 2), indicating the presence of active endometriosis.

The uterine junctional zone and endometrium showed normal thickness, with no criteria for classical diffuse adenomyosis, or images suggestive of adenomyomas.



Adenomyosis is characterised by the presence of ectopic endometrial glands and stroma within the myometrium, whose involvement can be focal or diffuse [1–3]. The inner third of the myometrium might be affected in the case of internal adenomyosis, or the outer two-thirds in the case of external adenomyosis [3]. In external adenomyosis, the junctional zone is spared, and it occurs due to the involvement of the serosa. It can be classified as anterior or posterior, in relation to its location in the myometrial wall, being more frequent posteriorly, in line with the high frequency of posterior deep infiltrating endometriosis (DIE), from where it seems to stem in an “outside-in” invasion of the myometrium [3–5].

Clinical perspective

The clinical manifestations are nonspecific, ranging from asymptomatic to disabling symptoms, namely pelvic pain, dyspareunia, severe dysmenorrhea and menometrorrhagia, which can lead to anaemia. External adenomyosis is more frequent in younger, nulligravid patients, being more frequently associated with infertility when compared to classical internal adenomyosis. It is also often associated with DIE [3–6].

Imaging perspective

Both MRI and TVUS are considered highly accurate imaging tools for non-invasive diagnosis of adenomyosis [1–3]. On MRI, external adenomyosis is reported in the presence of a nodular hypointense extrinsic infiltration of the subserosal myometrium on T2WI, with ill-defined borders, more frequently involving the posterior wall, with coexisting DIE [7]. Millimetric hyperintense elements on T2WI within the myometrium can also be seen, corresponding to small internal cysts. When they present haematic content, then a highly specific sign for this diagnosis can be seen, where they show hyperintensity on T1WI [1,4].


Therapeutic management of external adenomyosis cases may include medical management with hormonal therapy, such as progestins, or combined hormonal contraceptives, which may play a role in pain reduction and relief of gastrointestinal symptoms. Surgical intervention can also be considered, which may be conservative, or include radical resection of the affected organs. Imaging plays a crucial role in therapy planning, especially by assessing disease extent, and identifying complications such as bowel obstruction, aiding an optimal surgical approach and management [8,9].

Take home message / Teaching points

External adenomyosis is more frequently encountered in younger, nulligravid patients. It spares the junctional zone and involves the serosa, being frequently associated with DIE, from which it seems to arise, affecting more commonly the posterior myometrial wall. Imaging findings include a bulky subserosal thickening of the subserosal myometrium and small internal cysts with haematic content.

Differential Diagnosis List
Deep infiltrating endometriosis
Uterine adenomyoma
Uterine leiomyoma
Uterine leiomyosarcoma
External adenomyosis
Final Diagnosis
External adenomyosis
Case information
DOI: 10.35100/eurorad/case.18517
ISSN: 1563-4086