A 48-year-old multiparous woman presents with a 2-year history of progressive secondary dysmenorrhea, menorrhagia, and chronic pelvic pain. On bimanual examination, the uterus is tender, globular, and uniformly enlarged to approximately 12 weeks size with a soft, boggy consistency. Transvaginal ultrasound shows a diffusely thickened, trabeculated myometrium with small cystic foci and heterogeneous echotexture, as marked **A** in the diagram. MRI confirms junctional zone thickness of 14 mm with a junctional-to-myometrial ratio of 45%. Histopathology from a recent biopsy demonstrates endometrial glands and stroma within the myometrium accompanied by reactive smooth muscle hyperplasia. Which of the following best explains the gross and histological appearance of the structure marked **A**?
A. Diffuse adenomyosis with smooth muscle hyperplasia and ectopic endometrial tissue invading deep into the myometrium
B. Uterine leiomyomatosis with multiple firm, well-demarcated intramural fibroids
C. Focal adenomyoma with a well-circumscribed nodular lesion and distinct pseudocapsule
D. Endometriosis with peritoneal implants and chocolate cysts within the myometrial wall
Explanation
Why "Diffuse adenomyosis with smooth muscle hyperplasia and ectopic endometrial tissue invading deep into the myometrium" is right
The structure marked A — the diffusely thickened, trabeculated myometrium — is the pathological hallmark of adenomyosis. Adenomyosis is defined histologically as the presence of endometrial glands and stroma within the myometrium, deep to the endomyometrial junction, accompanied by reactive smooth muscle hyperplasia. The gross appearance of diffuse adenomyosis is a diffusely enlarged, globular ("boggy") uterus with a thickened, trabeculated cut surface and small blood-filled cystic spaces—exactly what is depicted in the diagram. The patient's clinical presentation (secondary dysmenorrhea, menorrhagia, tender enlarged soft uterus) and imaging findings (junctional zone >12 mm, ratio >40%, heterogeneous echotexture) are all consistent with diffuse adenomyosis, the most common pattern, which typically affects multiparous women in the 4th–5th decades (Williams Gynecology 4e; ACOG; Munro 2024).
Why each distractor is wrong
Focal adenomyoma with a well-circumscribed nodular lesion and distinct pseudocapsule: While focal adenomyosis (adenomyoma) is a recognized variant of adenomyosis, it presents as a circumscribed, nodular lesion that may mimic a leiomyoma. The diagram shows diffuse, trabeculated thickening throughout the myometrium, not a focal mass—this is diffuse adenomyosis, not the focal variant.
Uterine leiomyomatosis with multiple firm, well-demarcated intramural fibroids: Leiomyomas are firm, well-circumscribed lesions with a distinct pseudocapsule. They do not show the diffuse trabeculated appearance or the small blood-filled cystic spaces characteristic of adenomyosis. Leiomyomas are a key differential diagnosis but do not match the histological finding of ectopic endometrial glands and stroma with smooth muscle hyperplasia.
Endometriosis with peritoneal implants and chocolate cysts within the myometrial wall: Endometriosis is primarily a peritoneal disease and frequently coexists with adenomyosis but is not the same entity. The histological definition of adenomyosis specifically requires endometrial tissue deep within the myometrium below the endomyometrial junction, not peritoneal implants. Chocolate cysts are ovarian manifestations of endometriosis, not myometrial adenomyosis.
High-YieldNEET PG
Adenomyosis = diffuse myometrial invasion by ectopic endometrial glands + stroma + smooth muscle hyperplasia; diffuse type is most common; presents in multiparous women 4th–5th decade with secondary dysmenorrhea, menorrhagia, and tender boggy uterus.
Williams Gynecology 4e; ACOG; Munro 2024 review
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