Kidney tumor
Other adult malignancies

Author: Sean R. Williamson, M.D.

Revised:19 April 2018, last major update June 2012

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Leiomyosarcoma kidney

Cite this page: Williamson, S.R. Leiomyosarcoma. website. Accessed December 11th, 2018.
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

Images hosted on PathOut server:

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