Mesenchymal tumors

Benign metastasizing leiomyoma

Last author update: 1 August 2015
Last staff update: 23 June 2022 (update in progress)

Copyright: 2003-2022,, Inc.

PubMed Search: Benign metastasizing leiomyoma [title]

Roseann Wu, M.D., M.P.H.
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Cite this page: Wu R. Benign metastasizing leiomyoma. website. Accessed December 7th, 2022.
Definition / general
  • Benign appearing smooth muscle tumor in lung
  • Generally thought to represent hematogenous spread from a uterine leiomyoma, given evidence of clonal derivation (Mod Pathol 2006;19:130)
  • Alternately, may be metastasis of a well differentiated leiomyosarcoma of low malignant potential
  • Metastasizing leiomyoma
  • First described by Steiner in 1939 as "metastasizing fibroleiomyoma of the uterus"
  • Older term was "multiple fibroleiomyomatous hamartomas", when thought to originate in lung
  • Rare, ~100 cases reported in literature
  • Usually women of reproductive age or older, 36-64 years, mean 44 years, with history of uterine leiomyoma
  • Youngest patient reported is 23 years old (Am J Clin Oncol 2003;26:473)
  • Lung is most common site, but typically spares bronchus and pleura
  • Also reported at various other sites, including lymph nodes, retroperitoneum, skin, bone, spine, skull base, heart
  • Multiple nodules, occasionally cystic
  • Few millimeters to few centimeters in size
  • May be synchronous with uterine leiomyoma or found following hysterectomy or myomectomy for uterine leiomyoma
  • May show synchronous implants at other body sites
  • Estrogen and progesterone likely play a role, as lesions tend to regress during pregnancy or after oophorectomy
  • Lesions in postmenopausal women tend to grow slowly or stabilize
  • Mean duration between hysterectomy and appearance of lung lesions is ~15 years (Virchows Arch 2000;437:284)
Clinical features
  • Majority are asymptomatic
  • May present with dyspnea, cough, hemoptysis, chest pain
  • May rarely lead to respiratory failure in cases of bulky disease
  • Open lung biopsy and history of uterine leiomyomas
Radiology description
  • Chest Xray: diffuse, bilateral nodular opacities; rarely associated with miliary pattern (J Thorac Dis 2014;6:E92), cavitary lesions, multiloculated cysts, interstitial lung disease
  • CT: multiple, diffuse, well-defined, nodular, non-enhancing soft tissue lesions
  • PET: negative
Prognostic factors
  • Large tumors may lead to emboli, pulmonary infarction or symptomatic disease
Case reports
  • No consensus due to low morbidity and rarity
  • Surveillance acceptable for indolent, asymptomatic disease
  • Hysterectomy, bilateral oophorectomy, long term hormonal therapy (progestins and aromatase inhibitors) and GnRH agonists are options for disease control
  • Surgical palliation could be considered for large lesions to prevent massive hemoptysis, but is debated
Gross description
  • Solitary or multiple, tan-white, well-circumscribed, round to ovoid, firm nodules
  • Whorled cut surface
Gross images

Images hosted on other servers:
Mass and nodule

Mass and nodule

Well marginated, ovoid, firm

Well marginated, ovoid, firm

Pulmonary wedge

Pulmonary wedge

Microscopic (histologic) description
  • Well circumscribed, solitary or multiple nodules of smooth muscle, similar to uterine counterparts
  • Whorled to intersecting fascicles of ovoid to elongated spindled cells with abundant eosinophilic cytoplasm, oval to cigar or "boxcar-shaped" nuclei, inconspicuous nucleoli
  • Large, irregular, thick walled vessels
  • May contain cysts or entrapped epithelium
  • No atypia, no necrosis, no vascular invasion, no mitotic figures
Microscopic (histologic) images

Images hosted on other servers:
Lung tumor in left S4

Lung tumor in left S4

Multiple nodules

Multiple nodules

Desmin, AE1 / AE3, ER

Cytology description
  • Generally acellular or paucicellular on fine needle aspiration
  • Nonspecific cytologic findings: clusters of uniform, bland, cohesive spindle cells with no mitoses, no necrosis, and no significant atypia
Cytology images

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FNA, large clusters of spindle shaped cells FNA, large clusters of spindle shaped cells

FNA, large clusters of spindle shaped cells

Positive stains
Molecular / cytogenetics description
Differential diagnosis
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