The pathology of the uterus body including the endometrium and the myometrium

1. UTERUS BODY PATHOLOGY
DR. MONA RASHED

2. BODY OF UTERUS
• The uterine corpus is composed of endometrial
mucosa and the underlying smooth muscle
myometrium

3. ENDOMETRITIS
• Inflammation of the endometrium is classified as acute or chronic.
• Endometritis is commonly due to N. gonorrhoeae or C. trachomatis.
• Endometritis also may be due to retained products of conception, or to
presence of a foreign body such as an intrauterine device.
• Retained tissue or foreign bodies act as a nidus for ascending infection by
vaginal or intestinal tract flora.

4. ENDOMETRITIS; cont.
• Histologic examination reveals a neutrophilic infiltrate
coexisting with a stromal lymphoplasmacytic infiltrate in the
superficial endometrium and glands
• Clinically, endometritis manifest with fever, abdominal pain,
and menstrual abnormalities.

5. ADENOMYOSIS
• Adenomyosis refers to the growth of the basal layer of the
endometrium down into the myometrium.
• Nests of endometrial stroma, glands, or both, are found deep in the
myometrium interposed between the muscle bundles.
• The presence of endometrial tissue induces reactive hypertrophy of
the myometrium, resulting in an enlarged uterus, with a thickened
uterine wall.

7. ADENOMYOSIS; cont.
• Because the glands in adenomyosis derive from the stratum
basalis of the endometrium, they do not undergo cyclic
bleeding.
• Clinically; adenomyosis may produce menorrhagia,
dysmenorrhea, and pelvic pain before the onset of
menstruation.

8. ENDOMETRIOSIS
• Definition: Endometrial glands or stroma outside the uterus
• Common sites of endometriosis: Ovaries, uterine ligaments,
recto-vaginal septum and pelvic peritoneum, scars, umbilicus,
vagina, vulva and appendix

9. ENDOMETRIOSIS; cont.
• Three hypotheses explain the endometriosis:
1. The regurgitation theory, menstrual backflow through the
fallopian tubes leads to implantation.
2. The metaplastic theory, endometrial differentiation of
coelomic epithelium (from which endometrium originates) as
the source.
3. Vascular or lymphatic dissemination theory.

11. ENDOMETRIOSIS; MORPHOLOGY
• Endometriosis almost always contains functioning endometrium,
which undergoes cyclic bleeding with menstruation.
• Because blood collects in these foci, they usually appear grossly as
red-brown nodules.
• When the ovaries are involved, the lesions may form large, blood-
filled cysts that turn brown (chocolate cysts) as the blood ages.

13. ENDOMETRIOSIS; MORPHOLOGY; cont.
• Organization of the blood causes widespread fibrosis, leading to
adhesions among pelvic structures, sealing of the tubal fimbriated
ends, and distortion of the oviducts and ovaries.
• Clinical Effects of endometriosis: Infertility, dysmenorrhea, pelvic
pain
• The histologic diagnosis at all sites is the presence of: endometrial
glands, endometrial stroma, and hemosiderin pigment (old blood).

15. PROLIFERATIVE LESIONS OF THE
ENDOMETRIUM AND MYOMETRIUM

16. PROLIFERATIVE LESIONS OF THE
ENDOMETRIUM AND MYOMETRIUM
• The most common proliferative lesions of the uterine corpus
are:
1. Endometrial hyperplasia
2. Endometrial carcinomas
3. Endometrial polyps
4. Smooth muscle tumors: leiomyoma & leiomyosarcoma
• All tend to produce abnormal uterine bleeding as their
earliest manifestation.

17. Endometrial Hyperplasia
• Excess of estrogen, can induce exaggerated endometrial
proliferation (hyperplasia), which is an important precursor
of endometrial carcinoma.
• Causes of estrogen excess include
1. Anovulation
2. Polycystic ovarian disease
3. Functioning granulosal cell tumors of ovary
4. Estrogen replacement therapy
5. Obesity, as adipose tissue converts steroid precursors into estrogens.

18. Classification of endometrial hyperplasia
1. Hyperplasia Without Atypia (low grade)
– Simple hyperplasia:. Rarely progress to carcinoma
– Complex hyperplasia: Glandular crowding and branching with a complex growth
pattern. Less than 5% progress to carcinoma
2. Atypical Hyperplasia (high grade)
– Histopathology: there are atypical cellular and nuclear features.
Approximately 25% progress to carcinoma

19. Endometrial Carcinoma
• Usually arise in postmenopausal women; between the ages of
55 and 65 years
• Often present with postmenopausal bleeding
• Endometrial carcinomas comprise two distinct kinds of cancer:
endometrioid and serous carcinoma of the endometrium.

20. Endometrial Carcinoma; pathogenesis
• The endometrioid type accounts for 80% of cases of endometrial
carcinomas.
• Risk factors for endometrioid carcinoma include:
(1) Obesity
(2) Diabetes
(3) Hypertension
(4) Infertility
(5) Exposure to unopposed estrogen.
• Prolonged estrogen replacement therapy and estrogen-secreting ovarian
tumors increase the risk of endometrioid type of endometrial carcinoma.
• The serous type of endometrial carcinoma is much less common.

21. Endometrial Polyps
• Sessile lesions range from 0.5 to 3 cm in diameter.
• Larger polyps may project from the endometrial mucosa into the
uterine cavity.
• On histologic examination, they are composed of endometrium
resembling the basalis, frequently with small muscular arteries.
• Clinically; endometrial polyps cause abnormal uterine bleeding.
• Commonly are detected around the time of menopause.

23. Leiomyoma
• Benign tumors that arise from the smooth muscle cells in the
myometrium; termed leiomyomas.
• Leiomyomas are the most common benign tumor in females,
affecting 30% to 50% of women of reproductive age.

24. Leiomyoma; morphology
• Leiomyomas are typically well circumscribed, firm gray-white masses with
a characteristic whorled cut surface.
• They may occur singly, or multiple within the uterus myometrium, ranging
from small nodules to large tumors.
• Leiomyoma may be embedded within the myometrium (intramural),
whereas others may lie directly beneath the endometrium (sub-mucosal)
or directly beneath the serosa (sub-serosal).
• On histologic examination, the tumors are characterized by bundles of
smooth muscle cells mimicking the appearance of normal myometrium.

27. Leiomyoma; Clinically
• The most frequent presenting sign is menorrhagia, with or
without metrorrhagia.
• Large leiomyomas may be palpated by the affected woman or
may produce a dragging sensation.
• Leiomyomas almost never transform into sarcomas, and the
presence of multiple lesions does not increase the risk of
malignancy.

28. Leiomyosarcoma
• Leiomyosarcomas do not arise from a preexisting leiomyomas.
• They are almost always solitary and most often occur in postmenopausal
women, in contradistinction to leiomyomas, which frequently are multiple
and usually arise premenopausally.
• Leiomyosarcomas typically take the form of soft, hemorrhagic, necrotic
masses.
• Recurrence after removal is common, and they metastasize, typically to the
lungs.

29. References:
ROBBINS Basic Pathology; 9th edition. Chapter 19: Female
genital system and breast; Body of uterus, pages: 689-694