Kidney tumor
Other tumors

Topic Completed: 1 June 2012

Minor changes: 30 September 2019

Copyright: 2003-2019,, Inc.

PubMed Search: Leiomyosarcoma kidney

Sean R. Williamson, M.D.
Page views in 2019: 853
Page views in 2020 to date: 441
Cite this page: Williamson SR. Leiomyosarcoma. website. Accessed July 13th, 2020.
Definition / general
  • Rare, < 200 cases reported; 0.12% of all invasive renal malignancies
  • Mean age 58 years, range 40 - 75 years; 70% women in one study
  • Median overall survival is 25 months, 5 year overall survival is 25% (Can J Urol 2007;14:3435)
  • Patients usually die of disease, particularly if intermediate or high grade tumors (Am J Surg Pathol 2004;28:178)
Case reports
Gross description
  • Mean 14 cm, usually circumscribed and encapsulated with firm and whorled cut surface
  • Usually necrosis
Gross images

AFIP images

Tumor is solid nodule

Arising from bifid pelvis

Images hosted on other servers:

Necrosis and compressed rim of kidney parenchyma

Necrosis, hemorrhage and focal dilated kidney

Various images

Microscopic (histologic) description
  • Alternating fascicles of spindle cells with eosinophilic cytoplasm and blunt ended, nontapering nuclei
  • Usually focal necrosis (< 50% of specimen), often myxoid areas
  • Mean 10 mitotic figures / 10 HPF but wide range (3 - 43 mitotic figures / 10 HPF)
  • Minimal inflammation; occasional vascular invasion
  • Usually no epithelioid cells or marked pleomorphism
Microscopic (histologic) images

Images hosted on other servers:

(a) Spindle cells, (b) cells with pleomorphic nuclei

Various images

SMA+, keratin-

Negative stains
Differential diagnosis
  • Angiomyolipoma: triphasic, may have degenerative changes but no marked atypia, no mitotic activity, positive for melanocytic markers
  • Leiomyoma: not infiltrative, no atypia, no mitotic figures, no necrosis
  • Sarcomatoid renal cell carcinoma: more pleomorphic, no alternating fascicles, usually no smooth muscle morphology, usually keratin+ and muscle marker negative
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