Soft tissue
Skeletal muscle
Rhabdomyoma
Adult type rhabdomyoma
Author: Vijay Shankar, M.D.
Topic Completed: 1 November 2012
Minor changes: 20 January 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Rhabdomyoma [title] adult
Table of Contents
Definition / general | Clinical features | Case reports | Treatment | Clinical images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Cytology images | Positive stains | Negative stains | Electron microscopy description | Differential diagnosisCite this page: Shankar V. Adult type rhabdomyoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueadultrhabdomyoma.html. Accessed February 27th, 2021.
Definition / general
- Benign tumor of mature skeletal muscle
- Extracardiac rhabdomyomas are divided into fetal, adult and genital histologic types (eMedicine)
- Extracardiac tumors are not associated with tuberous sclerosis
- Some cases may be due to degeneration and regeneration, and not be neoplastic (Am J Surg Pathol 1989;13:791), but see Head Neck 2006;28:275
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
- 43 year old man with diagnosis of adult rhabdomyoma by fine needle aspiration cytology (Acta Cytol 2010;54:968)
- Elderly woman with intraoral multifocal adult rhabdomyoma (Arch Pathol Lab Med 1983;107:638)
- Adult rhabdomyoma of the extremity (Hum Pathol 2000;31:1074)
- Rhabdomyoma of the parapharyngeal space presenting with dysphagia (Dysphagia 2008;23:202)
Treatment
- Excision is curative, but may recur if incompletely excised
Clinical images
Contributed by Mark R. Wick, M.D.
Base of tongue, CT
Gross description
- Median 3 cm, circumscribed, soft, tan-red-brown
- Nodular or lobulated
Gross images
Contributed by Mark R. Wick, M.D.
Base of tongue
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
AFIP images
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
Contributed by Mark R. Wick, M.D.
Various images
Images hosted on other servers:
Large closely packed polygonal cells up to 150 microns
Abundant eosinophilic and granular cytoplasm
Actin+
Desmin+
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
- Muscle specific actin, desmin and myoglobin (100%)
- PAS+, diastase sensitive (detects glycogen)
- PTAH and Masson trichrome highlight cross striations and rod-like inclusions
Electron microscopy description
- Myofilaments, Z bands, glycogen granules
Differential diagnosis
- Alveolar soft part sarcoma
- Crystal storing histiocytosis
- Granular cell tumor: no skeletal muscle differentiation, no glycogen, smaller cells have poorly defined cell borders, often overlying pseudoepitheliomatous hyperplasia, S100+
- Hibernoma: no skeletal muscle differentiation, no glycogen
- Paraganglioma: NSE+, synaptophysin+, chromogranin+
- Well differentiated rhabdomyosarcoma
