Eye
Orbit and optic nerve
Rhabdomyosarcoma of orbit

Author: Nat Pernick, M.D. (see Authors page)

Revised: 16 May 2018, last major update November 2015

Copyright: (c) 2004-2018, PathologyOutlines.com, Inc.

PubMed Search: rhabdomyosarcoma[title] orbit

Cite this page: Pernick, N. Orbit and optic nerve: rhabdomyosarcoma of orbit. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/eyeorbitrms.html. Accessed September 22nd, 2018.
Definition / general
  • Most common orbital sarcoma in childhood
  • Usually embryonal and alveolar subtypes (alveolar more aggressive)
  • Often rapid onset of unilateral proptosis
  • May occur after radiation therapy for retinoblastoma, close to previously irradiated fields
  • Tumors in retinoblastoma patients may have rosette-like structures
  • References: Am J Surg Pathol 1998;22:1351 (post radiation therapy for bilateral retinoblastoma)
Radiology images

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CT shows large tumor of orbital floor invading maxillary sinus

Clinical images

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Botryoid tumor beneath the conjunctiva

Whole mount images

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Large tumor has infiltrated orbit

Microscopic (histologic) description
  • Syncytium of strap cells with abundant eosinophilic cytoplasm
  • Also closely packed small round cells with scanty cytoplasm, coarse nuclear chromatin and increased mitotic activity
  • Many have minimal rhabdomyoblastic differentiation except in occasional mature strap cells with cross striations
  • Alveolar pattern has fibrovascular septa resembling lung alveoli
Microscopic (histologic) images

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#1: alveolar pattern; #2: alveolar spaces contain anaplastic cells; #3: alveolar pattern and large anaplastic giant cells; #4: rhabdomyoblasts


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#1: embryonal pattern; #2: bundles of spindle cells with hyperchromatic nuclei and numerous mitotic figures; #3: cross striations; #4: myxoid pattern


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Round and tadpole shaped rhabdomyoblasts

Cytology images

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Long cytoplasmic processes and atypical
nuclei (inset - muscle specific actin positive)

Negative stains
  • CD99; Rb in retinoblastoma patients only