Soft tissue
Other tumors

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 16 September 2016, last major update November 2012

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

PubMed search: myxoma [title] soft tissue

Related topics: Cardiac, Carney complex, Fibromyxoma, Intramuscular, Jaw, Mazabraud syndrome, Superficial acral fibromyxoma

Cite this page: Myxoma. website. Accessed November 22nd, 2017.
Definition / general
  • Rare, benign, gelatinous lesion resembling fetal umbilical cord; often deep within muscle of extremity (Stanford University)
  • May derive from modified fibroblasts
  • Not a WHO diagnosis
  • Thigh, shoulder, upper arm
Clinical features
  • Diagnosis less likely if any of these findings: atypia, mitotic activity, more than occasional vessels, not intramuscular or juxtaarticular
Case reports
  • Excision; rarely recurs if adequately excised
  • Cellular cases appear to have same indolent behavior if completely excised (Histopathology 2001;39:287)
Gross description
  • Mucoid / gelatinous, often poorly circumscribed, may have infiltrative borders
  • May be up to 13 cm
Microscopic (histologic) description
  • Hypocellular, composed of bland cells, no mitotic activity, no lipoblasts, scant blood vessels; may have focal histiocytes
  • Slightly more cellular with collagenized capsule at periphery
  • May have areas of increased vascularity or be hypercellular (Am J Surg Pathol 1998;22:1222)
  • Slightly basophilic matrix with usually a few spindle cells at high power with oval nuclei
  • May have central mucinous cyst
  • At periphery, may infiltrate striated muscle and be associated with muscle atrophy
Microscopic (histologic) images
Images hosted on PathOut server:

Courtesy of Dr. Mark R. Wick

Images hosted on other servers:


Site unknown

Cytology description
  • Viscous, gelatinous quality when first applied to glass slide
  • Paucicellular, often finely granular myxoid stroma with few cells, usually macrophages and bland spindle cells (Am J Clin Pathol 2005;123:858)
Positive stains
Negative stains
Electron microscopy description
  • Fibroblast-like cell with prominent Golgi, endoplasmic reticulum, cytoplasmic filaments
Electron microscopy images
Images hosted on other servers:

Conjunctival myxoma

Molecular / cytogenetics description
Differential diagnosis