Lung tumor
Benign tumors
Benign metastasizing leiomyoma

Author: Roseann Wu, M.D. (see Authors page)

Revised: 20 December 2016, last major update August 2015

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Benign metastasizing leiomyoma [title]
Cite this page: Benign metastasizing leiomyoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lungtumorb9metastasizingleio.html. Accessed April 23rd, 2017.
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
Terminology
  • 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
Epidemiology
  • 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)
Sites
  • 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
Pathophysiology
  • 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
Diagnosis
  • Open lung biopsy and history of uterine leiomyomas
Radiology Description
  • Chest Xray: diffuse, bilateral nodular opacities; rarely associated with military 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
Treatment
  • 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:

Missing Image

Mass and nodule

Missing Image

Well marginated, ovoid, firm

Missing Image

Pulmonary wedge

Micro 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
Micro Images

Images hosted on other servers:

Missing Image

Lung tumor in left S4

Missing Image

Multiple nodules

Missing Image Missing Image Missing Image

Various images

Missing Image

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

Images hosted on other servers:

Missing Image Missing Image

FNA, large clusters of spindle shaped cells

Positive Stains
Molecular / Cytogenetics Description
Differential Diagnosis