Leiomyoma-general

Uterus

Smooth muscle tumors

Leiomyoma-general

Author: Mohamed Mokhtar Desouki, M.D., Ph.D.

Topic Completed: 1 August 2011

Minor changes: 18 January 2021

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

PubMed search: uterus [title] "leiomyoma"

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Table of Contents

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

Terminology

Also called fibroid, myofibroma, fibromyoma, leiomyofibroma, fibroma, myoma

Epidemiology

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

Etiology

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)

Treatment

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

H&E

Myeloperoxidase

CD34

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

Case #345

Vasculitis secondary to Lupron for leiomyomas

Images hosted on other servers:

Various images

Positive stains

Smooth muscle actin, muscle specific actin, desmin, h-caldesmon, vimentin
Focal cytokeratin in 25% - 30%, especially epithelioid cases
Occasionally focal CD10

Negative stains

Keratin (usually), EMA (usually)

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

Endometrial stromal sarcoma with smooth muscle metaplasia
Leiomyosarcoma