Soft tissue
Skeletal muscle
Adult type rhabdomyoma

Topic Completed: 1 November 2012

Minor changes: 26 March 2019

Copyright: 2002-2018,, Inc.

PubMed Search: Rhabdomyoma [title] adult

Vijay Shankar, M.D.
Page views in 2019: 3,961
Page views in 2020 to date: 2,667
Cite this page: Shankar V. Adult type rhabdomyoma. website. Accessed August 7th, 2020.
Definition / general
Clinical features
  • Very rare
  • Usually head and neck, particularly oral cavity
  • Median age 60 years, 75% male (Hum Pathol 1993;24:608)
  • May be multifocal (25%)
Case reports
  • Excision is curative, but may recur if incompletely excised
Clinical images

Base of tongue, CT
courtesy of Mark R. Wick, M.D.

Gross description
  • Median 3 cm, circumscribed, soft, tan-red-brown
  • Nodular or lobulated
Gross images

Base of tongue
courtesy of Mark R. Wick, M.D.

Microscopic (histologic) description
  • Well circumscribed, not encapsulated, sheets of large, well differentiated skeletal muscle cells
  • Cells are round or polygonal with abundant eosinophilic fibrillar or granular cytoplasm with frequent cross striations and intracytoplasmic rod-like inclusions
  • Nuclei are small, round and vesicular, may have prominent nucleoli
  • May have spider cells with vacuolated cytoplasm (cells resemble spider webs)
  • Variable glycogen and lipid
  • No mitotic activity, no atypia
Microscopic (histologic) images

Images hosted on PathOut servers:

Abundant eosinophilic and granular cytoplasm

Distinct well demarcated lobules of polygonal cells

Large closely packed polygonal cells up to 150 microns

Haphazardly arranged crystalline material resembling sarcomeric bands

Crystalline material resembles rods

Courtesy of Mark R. Wick, M.D.

Images hosted on other servers:

Large closely packed polygonal cells up to 150 microns

Abundant eosinophilic and granular cytoplasm

Various images



Cytology description
  • Fragments of tumor cells, which are large, polygonal cells
  • Cytoplasm is eosinophilic and finely granular, may resemble granular cell tumor, which is S100+, muscle markers- (Diagn Cytopathol 2009;37:483)
  • Eccentrically placed nuclei
  • Cross striations and inclusions are not conspicuous (Acta Cytol 2010;54:968)
Cytology images

Images hosted on other servers:

Various images

Positive stains
Negative stains
Electron microscopy description
  • Myofilaments, Z bands, glycogen granules
Differential diagnosis
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