Smooth muscle tumors

Topic Completed: 1 August 2011

Minor changes: 18 January 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed search: uterus [title] "leiomyoma"

Mohamed Mokhtar Desouki, M.D., Ph.D.
Page views in 2020: 49,560
Page views in 2021 to date: 3,128
Cite this page: Desouki M. Leiomyoma-general. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusleiomyoma.html. Accessed January 22nd, 2021.
Definition / general
  • Extremely common tumor
  • At autopsy, present in uterus in 77% of females; 84% of tumors are multicentric
  • Also called fibroid, myofibroma, fibromyoma, leiomyofibroma, fibroma, myoma
  • Present in 25% of women during reproductive years
  • More common in blacks than whites; usually multiple in blacks
  • Clinically apparent lesions are more common in nulliparous, postmenopausal women
  • May be due to xenoestrogens, a diverse set of environmental compounds which exist naturally (genistein) or are synthetic (diethylstilbestrol / DES) and bind to estrogen receptor (ER) in myometrium
  • Somatic mutations and molecular alterations in X chromosome must occur for initiation and subsequent development of myomas
  • Oral contraceptives and progestin-only injectables are associated with a reduced risk, particularly with prolonged use of oral contraceptives
  • Meat consumption may be a risk factor and green vegetables a protective factor (Obstet Gynecol 1999;94:395)
Clinical features
  • Typically asymptomatic, but up to 30% of women experience abnormal uterine bleeding or lower abdomen pressure related symptoms
  • May interfere with pregnancy or block ureters if large
  • Rarely associated with polycythemia, which regresses when the tumor is excised
  • Estrogen responsive, may regress after menopause or castration, and enlarge during pregnancy
  • Difficult to diagnose from D & C since resembles superficial myometrium
Case reports
  • 32 year old woman with vaginal bleeding for two weeks and well circumscribed uterine mass with hemorrhage foci (Case of the Week #429)
  • 49 year old woman with hysterectomy for fibroid uterus (Case of the Week #345)
  • If symptomatic, treat with myomectomy, leuprolide acetate depot, or GNRH analog that shrinks the tumor; asymptomatic tumors do not require treatment
Gross description
  • Sharply circumscribed, round, firm, grayish white, "raw silk" and whorled cut surface
  • Often shells out
  • Bulging and trabeculated cut surface
  • Usually within myometrium (intramural), may be submucosal or subserosal
  • May be multiple
  • Sampling: sample myxoid areas extensively to rule out myxoid leiomyosarcoma; sample all leiomyomas that lack the classic gross appearance of leiomyomas and 3 largest tumors
Gross images

AFIP images

Hysterectomy specimen

Images hosted on other servers:

Submucosal leiomyoma

Submucosal, intramural and subserosal leiomyomata

Microscopic (histologic) description
  • Whorled (fascicular) pattern of smooth muscle bundles separated by well vascularized connective tissue
  • Smooth muscle cells are elongated with eosinophilic or occasional fibrillar cytoplasm and distinct cell membranes
  • May develop areas of degeneration if large including hyaline or mucoid change, calcification, cystic change or fatty metamorphosis
  • Usually noninfiltrative, thick walled arteries throughout and cleft-like spaces
  • May have extensive hyaline necrosis if protrudes into endometrial cavity
  • Variable lymphocytes and mast cells
  • Usually less than 5 mitotic figures per 10 high power fields in most mitotically active area, no significant atypia
  • Rarely has focal skeletal muscle differentiation (Hum Pathol 1999;30:356) or tubules / glands
  • Post lupron treatment: initially edema and necrosis, then hyalinization and mild lymphocytic infiltrate

  • Smooth muscle proliferations with unusual growth patterns: disseminated peritoneal leiomyomatosis; benign metastasizing leiomyoma; intravenous leiomyomatosis; lymphangioleiomyomatosis
Microscopic (histologic) images
Scroll to see all images.

Case #429




AFIP images

Various images

Whorled fascicles of smooth muscle cells

Intersecting bands of small, uniform smooth muscle cells

Small spindle cells with uniform nuclei

Bland smooth muscle cells are entrapped and isolated within extensive fields of hyalinized stroma

Sharp demarcation of large field of hyalinization

Vascular leiomyoma
resembling hemangioma

Contributed by Dr. Mowafak Hamodat

Embolized leiomyoma

Embolized leiomyoma

Case #345

Vasculitis secondary to Lupron for leiomyomas

Vasculitis secondary to Lupron for leiomyomas

Images hosted on other servers:

Various images

Positive stains
Negative stains
Electron microscopy description
  • Smooth muscle cells with varying degrees of differentiation
  • In central regions, cells are characterized by filaments sporadically located in the cytoplasm and well developed organelles
  • In outer layer, myocytes are more mature and resemble normal myometrial cells
Molecular / cytogenetics description
  • 40% have nonrandom tumor specific chromosomal abnormalities; other 60% have normal chromosomal profiles
  • Most common chromosomal rearrangements are t(12;14)(q14-q15;q23-q24), deletion (7)(q22q32), rearrangement of 6-6p21 (Cancer Genet Cytogenet 2005;158:1)
  • Less common are karyotypic abnormal rearrangements of 1p36, 3q, 10q22, 13q21 - 22, trisomy 12 and X chromosome
  • Increase in transforming growth factor beta in leiomyomata tissue
  • Patients with germline mutations in fumarate hydratase have increased risk for developing leiomyomas, as well as uterine leiomyosarcomas
Differential diagnosis
Back to top
Image 01 Image 02