Endometrium and Myometrium PDF

## ENDOMETRIUM AND MYOMETRIUM ### I. BASIC PRINCIPLES - **Endometrium:** mucosal lining of the uterine cavity. - **Myometrium:** smooth muscle wall underlying the endometrium. - **Endometrium is hormonally sensitive:** - **Growth of the endometrium:** estrogen driven (proliferative phase)....

## ENDOMETRIUM AND MYOMETRIUM ### I. BASIC PRINCIPLES - **Endometrium:** mucosal lining of the uterine cavity. - **Myometrium:** smooth muscle wall underlying the endometrium. - **Endometrium is hormonally sensitive:** - **Growth of the endometrium:** estrogen driven (proliferative phase). - **Preparation of the endometrium for implantation:** progesterone driven (secretory phase). - **Shedding:** occurs with loss of progesterone support (menstrual phase). ### II. ASHERMAN SYNDROME - **Secondary amenorrhea:** due to loss of the basalis and scarring. - **Result of overaggressive dilation and curettage (D&C).** ### III. ANOVULATORY CYCLE - **Lack of ovulation.** - **Results in:** an estrogen-driven proliferative phase without a subsequent progesterone driven secretory phase. - Proliferative glands break down and shed resulting in uterine bleeding. - **Represents a common cause of dysfunctional uterine bleeding, especially during menarche and menopause.** ### IV. ACUTE ENDOMETRITIS - **Bacterial infection of the endometrium.** - **Usually due to:** retained products of conception (e.g. after delivery or miscarriage); retained products act as a nidus for infection. - **Presents as:** fever, abnormal uterine bleeding, and pelvic pain. ### V. CHRONIC ENDOMETRITIS - **Chronic inflammation of the endometrium.** - **Characterized by:** lymphocytes and plasma cells. - **Plasma cells are necessary for the diagnosis of chronic endometritis given that lymphocytes are normally found in the endometrium.** - **Causes include:** retained products of conception, chronic pelvic inflammatory disease (e.g. Chlamydia), IUD, and TB. - **Presents as:** abnormal uterine bleeding, pain, and infertility. ### VI. ENDOMETRIAL POLYP - **Hyperplastic protrusion of endometrium.** - **Presents as:** abnormal uterine bleeding. - **Can arise as a side effect of tamoxifen, which has anti-estrogenic effects on the breast but weak pro-estrogenic effects on the endometrium.** ### VII. ENDOMETRIOSIS - **Endometrial glands and stroma outside of the uterine endometrial lining.** - **Most likely due to:** retrograde menstruation with implantation at an ectopic site. - **Presents as:** dysmenorrhea (pain during menstruation) and pelvic pain; may cause infertility. - **Endometriosis cycles just like normal endometrium.** - **Most common site of involvement is the ovary, which classically results in formation of a 'chocolate' cyst.** - **Other sites of involvement include:** the uterine ligaments (pelvic pain), pouch of Douglas (pain with defecation), bladder wall (pain with urination), bowel serosa (abdominal pain and adhesions), and fallopian tube mucosa (scarring increases risk for ectopic tubal pregnancy); implants classically appear as yellow-brown 'gun-powder' nodules. - **Involvement of the uterine myometrium is called adenomyosis.** - **There is an increased risk of carcinoma at the site of endometriosis, especially in the ovary.** ### VIII. ENDOMETRIAL HYPERPLASIA - **Hyperplasia of endometrial glands relative to stroma.** - **Occurs as a consequence of unopposed estrogen:** (e.g. obesity, polycystic ovary syndrome, and estrogen replacement). - **Classically presents as:** postmenopausal uterine bleeding. - **Classified histologically based on architectural growth pattern:** (simple or complex) and the presence or absence of cellular atypia. - **Most important predictor for progression to carcinoma:** the presence of cellular atypia; simple hyperplasia with atypia often progresses to cancer (30%); whereas, complex hyperplasia without atypia rarely does (<5%). ### IX. ENDOMETRIAL CARCINOMA - **Malignant proliferation of endometrial glands.** - **Most common invasive carcinoma of the female genital tract.** - **Presents as:** postmenopausal bleeding. - **Arises via two distinct pathways:** hyperplasia and sporadic. - **In the hyperplasia pathway:** carcinoma arises from endometrial hyperplasia. - **Risk factors are related to estrogen exposure and include:** early menarche/late menopause, nulliparity, infertility with anovulatory cycles, and obesity. - **Average age of presentation:** 60 years. - **Histology is endometrioid.** - **In the sporadic pathway:** carcinoma arises in an atrophic endometrium with no evident precursor lesion. - **Average age at presentation:** 70 years. - **Histology is usually serous:** characterized by papillary structures, with psammoma body formation. - **p53 mutation is common, and the tumor exhibits aggressive behavior** ### X. LEIOMYOMA (FIBROIDS) - **Benign neoplastic proliferation of smooth muscle arising from myometrium; most common tumor in females.** - **Related to estrogen exposure:** - **Common in premenopausal women.** - **Often multiple.** - **Enlarge during pregnancy; shrink after menopause.** - **Gross exam shows multiple, well-defined, white, whorled masses that may distort the uterus and impinge on pelvic structures.** - **Usually asymptomatic; when present, symptoms include abnormal uterine bleeding, infertility, and a pelvic mass.** ### XI. LEIOMYOSARCOMA - **Malignant proliferation of smooth muscle arising from the myometrium.** - **Arises de novo; leiomyosarcomas do not arise from leiomyomas.** - **Usually seen in postmenopausal women.** - **Gross exam often shows a single lesion with areas of necrosis and hemorrhage; histological features include necrosis, mitotic activity, and cellular atypia.**