Lung

Mesenchymal tumors

Benign metastasizing leiomyoma



Last author update: 9 January 2023
Last staff update: 13 October 2023

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PubMed Search: Benign metastasizing leiomyoma

Ali Alzeer, M.D.
Roseann I. Wu, M.D., M.P.H.
Page views in 2024 to date: 1,036
Cite this page: Alzeer A, Wu R. Benign metastasizing leiomyoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumorb9metastasizingleio.html. Accessed April 14th, 2024.
Definition / general
  • Rare, benign appearing smooth muscle tumor in lung
  • Generally thought to represent hematogenous spread from a uterine leiomyoma, given evidence of clonal derivation / similarities in cytogenetic abnormalities (Mod Pathol 2006;19:130, Am J Surg Pathol 2007;31:737)
Essential features
  • Benign smooth muscle tumor in lung
  • Arises from hematogenous spread of uterine leiomyoma, usually years following surgical manipulation
  • Hormonally responsive
  • Multifocal; metastasis from leiomyosarcoma must be ruled out
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
ICD coding
  • ICD-O: 8898/1 - metastasizing leiomyoma
  • ICD-11: XH1EX8 - metastasizing leiomyoma
Epidemiology
Sites
Pathophysiology
  • Exact pathophysiology is unclear
  • Most accepted hypothesis in the literature is that lesions are clonally derived from uterine leiomyomas (Mod Pathol 2006;19:130, Am J Surg Pathol 2007;31:737)
  • Hormonally dependent; there is evidence of disease progression in pregnancy and regression after menopause
Etiology
  • Hematogenous spread (metastasis) from benign uterine leiomyoma, often after surgical manipulation (myomectomy or hysterectomy)
Clinical features
  • Asymptomatic; incidentally discovered on imaging
  • 30% of patients present with symptoms including chest pain, back pain, cough, dyspnea, hemoptysis, pneumothorax and respiratory failure
  • Lesions develop months to years after myomectomy; mean duration between hysterectomy and appearance of lung lesions is 23 years (Clin Chest Med 2016;37:589, Ann Thorac Surg 2016;101:253)
Diagnosis
Radiology description
Radiology images

Images hosted on other servers:

CT of benign metastasizing leiomyoma in lung

Prognostic factors
Case reports
Treatment
  • No specific guidelines for management
  • Watchful management for asymptomatic patients
  • Surgical resection of symptomatic lesions or lesions with interval growth
  • Medical hormonal suppression (J Clin Endocrinol Metab 2004;89:3183)
  • Oophorectomy for premenopausal women
Gross description
  • Tan-white, well circumscribed, rounded, rubbery to firm, with a whorled cut surface
Gross images

Contributed by Roseann Wu, M.D., M.P.H.

Homogenous whorled cut surface

Frozen section description
  • Bland spindle cell proliferation, arranged in fascicles
Microscopic (histologic) description
  • Well circumscribed, solitary or multiple nodules of smooth muscle, similar to uterine counterparts (BMC Pulm Med 2020;20:292, Case Rep Oncol Med 2014;2014:842801)
  • 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

Contributed by Roseann Wu, M.D., M.P.H.

Well circumscribed lesion

Bland spindle cells

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

FNA, large clusters of spindle shaped cells

Electron microscopy description
  • Spindle cells show basal lamina material, pinocytotic vesicles, intracytoplasmic microfilaments with focal densities
Molecular / cytogenetics description
Molecular / cytogenetics images

Images hosted on other servers:

PCR amplification of lung and uterine tumors

Telomere length by FISH

Videos

Benign metastasizing leiomyoma

Sample pathology report
  • Lung, left upper lobe, mass, wedge resection:
    • Low grade spindle cell neoplasm, consistent with benign metastasizing leiomyoma (see comment)
    • Comment: Patient’s history of uterine leiomyoma is noted. Immunohistochemical studies were performed with adequate controls on block (A1). The tumor cells are positive for SMA, actin, desmin, ER and PR. The tumor cells are negative for pankeratin, TTF1, HMB45, STAT6 and chromogranin. The morphology and immunohistochemical profile supports the above diagnosis.
Differential diagnosis
Board review style question #1

A 45 year old woman presents with multiple incidentally discovered, well circumscribed, bilateral lung nodules on CT scan. She is asymptomatic and her history is only notable for a myomectomy, 10 years ago. A biopsy of one of the nodules is performed (see figure above). On immunohistochemical staining, the lesion is negative for STAT6 and the Ki67 proliferative index is low. What is the most likely diagnosis?

  1. Benign metastasizing leiomyoma
  2. Leiomyosarcoma
  3. Pulmonary hamartoma
  4. Solitary fibrous tumor
Board review style answer #1
A. Benign metastasizing leiomyoma

Comment Here

Reference: Benign metastasizing leiomyoma
Board review style question #2

A 45 year old woman presents with multiple incidentally discovered, well circumscribed, bilateral lung nodules on CT scan. She is asymptomatic and her history is only notable for a myomectomy 10 years ago. A biopsy of one of the nodules is performed (see figure above). On immunohistochemical staining, the lesion is negative for STAT6 and the Ki67 proliferative index is low. Based on this specific clinical presentation, what is the best choice for treatment?

  1. Chemotherapy
  2. Follow up imaging
  3. Hormonal therapy
  4. Surgical resection
Board review style answer #2
B. Follow up imaging

Comment Here

Reference: Benign metastasizing leiomyoma
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