Other benign / low grade tumors

Author: Hanni Gulwani, M.D. (see Authors page)

Revised: 18 June 2018, last major update December 2012

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

PubMed Search: Fibromatosis mediastinum

Cite this page: Gulwani, H. Fibromatosis. website. Accessed July 19th, 2018.
Definition / general
  • Anterior or posterior mediastinum
  • Children and young adults
Clinical features
  • Associated with superior vena cava syndrome, nerve entrapment or dysphagia
Case reports
Gross description
  • Poorly demarcated (often receive in multiple fragments), gritty, tan-white, centered in soft tissue
Microscopic (histologic) description
  • Fibromyxoid matrix with paucicellular, bland tumor cells in parallel or fascicular patterns
  • Cells have dispersed chromatin, minimal nucleoli, eosinophilic or amphophilic cytoplasm
  • Thick walled venule sized vessels with open lumina
  • No staghorn vessels
  • No storiform growth, no nuclear pleomorphism, no / rare mitotic activity, no inflammatory infiltrate
Microscopic (histologic) images

Images hosted on other servers:

A: fusiform cells; B: myxoid degeneration

Positive stains
Electron microscopy description
  • Myofibroblastic features of intrareticular collagen fibers, thin filament bundles, cytoplasmic dense bodies