Pathology > Gynecologic > Uterine Corpus > Benign Neoplasms
Objectives Anat & Hist Physiologic Cond. Infections Benign Cond. Benign Neoplasms Premalignant Cond. Malignant Neoplasms

V. Benign Neoplasms and Tumor-like Lesions


After completing this section you will be able to:

  • list benign tumors and tumor-like conditions of the endometrium
  • describe their clinical features
  • describe/recognize histologic features
  • state clinical behavior and complications

  1. Endometrial polyp

They originate as focal hyperplasia of the basalis and develop into localized overgrowths of endometrial tissue covered by epithelium. Endometrial polyps are most common in women between 40 and 50 years.

Clinical appearances

The polyp may cause irregular bleeding. It may be broad-based and sessile, pedunculated or attached to the endometrium by a slender stalk. Most occur in the fundus and extend downwards. The size is variable from 1mm to a mass that fills the endometrial cavity. Occasionally a polyp may protrude through the external os. Grossly it is smooth, red or brown and dark red when infarcted.

Endometrial polyp attached to the fundus.


Composed of glands of variable size and shape, fibrotic stroma and thick-walled blood vessels. The relative amounts of the 3 components vary considerably from polyp to polyp.

Endometrial polyp. Many dilated blood vessels are present.

Clinical behavior

Endometrial polyps are benign with no malignant potential but malignant tumors may be found in them. When this occurs the prognosis is more favorable provided the tumor has not extended beyond the base.

Question: What other lesions may present as a "polyp" in the endometrium?


  1. Leiomyoma (Fibroid)

Leiomyoma is a benign tumor of smooth muscle origin. It is the most common neoplasm of the female genital tract and probably in women and is more common in black than white women.

Clinical and gross appearances

Patients may present with irregular bleeding, pelvic pain, pelvic mass, infertility. The tumor is estrogen responsive and may undergo rapid increase in size during pregnancy. In about 70% of patients it is multiple. Leiomyoma may be located anywhere in the myometrium.

Submucosal tumors are overlain by compressed endometrium, may be pedunculated and occasionally protrude though the cervix.

Intramural tumors, the most common, lie within the myometrium.

Subserosal fibroids lie beneath the serosal covering of the uterus or are pedunculated and attached to the serosa. Pedunculated ones may undergo torsion and infarction or loose their connection to the uterus and become attached to another pelvic organ forming a "parasitic leiomyoma".

The tumors appear as well circumscribed, spherical, dense and firm-to-hard masses with whorled, tan-white cut surfaces.

Leiomyoma. Note whorled cut surface.


Microscopically, there are interlacing bundles of smooth muscle cells with collagenous stroma between bundles.

Leiomyoma composed of interlacing fibers of bland smooth muscle.

Degenerative changes may be seen. These take the form of:

Atrophy — the tumor reduces in size at menopause or after pregnancy following drop in estrogen level.

Hyaline change (hyalinization) — histologic appearance in which the neoplastic smooth muscle cells and collagen fibers loose their detail and appear to fuse and take on a homogeneous, acellular, glassy eosinophilic appearance. Usually occurs as the tumor "ages".

Myxoid and cystic change — myxoid change results from marked increase in mucoid ground substance such that the affected areas come to resemble myxoid tissue of the umbilicus. Liquefaction occurs after extreme myxoid change leading to formation of cysts.

Calcification — common in menopausal women. Circulatory deprivation leads to precipitation of calcium salts within the tumor. Usually occurs in areas of hyalinization.

Septic — Infection may follow necrosis of the center due to circulatory inadequacy.

Red (carneous) — venous thrombosis and congestion with interstitial hemorrhage may occur, most commonly in pregnancy. This is usually accompanied by pain, which may produce a clinical picture of acute abdomen.

Clinical behavior

This is a benign tumor with no appreciable malignant potential (incidence of malignant transformation is 0.1-0.5%). It may cause anemia from heavy bleeding in non-pregnant women, or urinary or bowel obstruction (subserosal or parasitic tumors).

Question: What type of anemia may be caused by uterine leiomyoma?

Question: What complications may arise in pregnancy?


Objectives Anat & Hist Physiologic Cond. Infections Benign Cond. Benign Neoplasms Premalignant Cond. Malignant Neoplasms