Adenomyosis
Synonyms/Description
Endometriosis of the uterus or myometrium
Etiology
Adenomyosis is defined pathologically when endometrial glands and stroma are found in the myometrium, distant from the endometrial cavity itself. This ectopic endometrial tissue has the ability to induce hypertrophy of the surrounding myometrium. This process can be focal or diffuse and thus accounts for the variability in the ultrasound appearances noted. The endometrium-myometrium junctional zone is jagged and fuzzy because the endometrial mucosa essentially invades the underlying myometrium, thus blurring the interface between these two, typically distinct zones. (This may be focal or global.)
Ultrasound Findings
Generalized Adenomyosis
The uterus is typically enlarged and globular with heterogeneous myometrium, which is typically wider on one side than the other. The heterogeneous myometrium often contains myometrial cysts, which likely represent areas of glandular dilatation or hemorrhage caused by repeated bleeding. These cysts are also frequently seen in a subendometrial location.
Adenomyoma
An adenomyoma appears as a focal, somewhat circumscribed island of heterogeneity in the myometrium, suggesting a fibroid, but typically without clear borders. When the borders are sharp, one cannot distinguish an adenomyoma from a fibroid. The adenomyoma may project into the cavity in the form of a broad-based polyp (polypoid adenomyoma).
Three-dimensional (3-D) ultrasound is helpful to demonstrate the multitude of linear hyperechoic bands emanating from the endometrium into the myometrium, producing the shaggy outline of the endometrial cavity on 3-D coronal view of the uterus.
Although magnetic resonance imaging (MRI) has been useful for diagnosing adenomyosis, it is unnecessary because ultrasound has similar accuracy. A comparison between ultrasound and MRI was reported using 23 articles (involving 2312 women). Transvaginal ultrasound had a sensitivity and specificity of 72% and 81%, respectively, whereas MRI had a sensitivity and specificity of 77% and 89%, respectively.
Doppler evaluation of adenomyosis usually does not add to the diagnosis because the amount of vascularity is variable and nonspecific.
Differential Diagnosis
If the area of adenomyosis is focal, it may be confused with a fibroid or a polyp if it projects into the endometrial cavity. Because of the lucencies and heterogeneities in the myometrium, uterine malignancy (though very rare) is sometimes considered. The clue to the correct diagnosis is the asymmetry of the width of the myometrium comparing the posterior to the anterior aspect on longitudinal view as well as the shaggy appearance of the endometrial echo in a patient with chronic pain and abnormal bleeding.
Clinical Aspects and Recommendations
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