Soft tissue
Smooth muscle
Myxoid leiomyosarcoma

Author: Vijay Shankar, M.D.

Revised: 31 January 2018, last major update November 2012

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Myxoid leiomyosarcoma [title] soft tissue

Cite this page: Shankar, V. Myxoid leiomyosarcoma. website. Accessed March 21st, 2018.
Definition / general
  • Defined as 50%+ myxoid stroma
  • Rare; 75% women, median age 58 years, range 22 - 84 years
Clinical features
  • Usually affects chest, female genitalia (particularly uterus), head and neck, limbs
  • 40% recur, 15% metastasize, 17% have tumor related deaths (Am J Surg Pathol 2000;24:927)
  • Recur and metastasize regardless of mitotic count (which is deceptively low due to hypocellularity, Histopathology 1985;9:159)
Case reports
Gross description
  • Large gelatinous mass
  • Well circumscribed
  • May have cystic change, necrosis and hemorrhage
Microscopic (histologic) description
  • Invasive and infiltrative
  • Fascicular, reticular, microcystic or resembling myxofibrosarcoma
  • Spindled cells with smooth muscle features surrounded by abundant basophilic (myxomatous) material composed of hyaluronic acid
  • Tumor cells have moderate to marked atypia but variable tumor cell necrosis
  • May have focal epithelioid cells
  • Usually low grade
  • Deceptively low mitotic rates are due to hypocellularity
Microscopic (histologic) images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

Images hosted on other servers:

Various images

Smooth muscle differentiation

Cytology description
  • Resembles low to intermediate grade myxofibrosarcoma
  • Diffusely granular myxoid stroma is accompanied by randomly distributed spindled or ovoid tumor cells, either solitary or in large cohesive cellular clusters
  • Nuclei are round to ovoid, moderately pleomorphic and contain small / inconspicuous nucleoli (Cancer 2000;90:167, Acta Cytol 2000;44:415)
  • Peritoneal washing of disseminated uterine tumor: uniformly dispersed spindly to polygonal epithelioid tumor cells focally linked by background matrix
  • Spindled tumor cells attach to and radiate from branching capillary structures
  • Occasional scattered signet-ring cells
  • The background mucoid substance is more conspicuous in cell block (Diagn Cytopathol 2002;27:47)
Cytology images

Images hosted on other servers:

Figures 7 - 9

Positive stains
Negative stains
Differential diagnosis