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Ocular System

Orbital rhabdomyosarcomas (RMS)

Ocular RMS comprises tumors that occur in the orbit, or rarely in other ocular adnexal structures or within the eye.

Ocular RMS comprises tumors that occur in the orbit, or rarely in other ocular adnexal structures or within the eye.

Rhabdomyosarcoma (RMS):

Highly malignant tumor in which the tissue of origin is pluripotent mesenchyme.
  • M/C soft-tissue sarcoma of the head and neck in childhood
    • 4% of all pediatric malignancies
    • 10% of all cases occur in the orbit

Classification

Histological subgroups:

  • Embryonal variant (M/C, 80% cases)
  • Alveolar variant (worst prognosis): Small round, densely appearing cells loosely arranged with septae similar to lung alveoli
  • Botryoid variant: Subepithelial grape-like aggregates of tumour cells
  • Pleomorphic variant

Clinical features

  • Proptosis developing rapidly over weeks (80–100% cases)
  • Globe displacement (80% cases) which is usually downward and outward because two-thirds of these tumors are supero-nasal

Diagnosis

Imaging:

USG, CT-scan, MRI
MR orbits and brain. Large intraorbital mass with local invasion of the lamina papyracea and no intracranial extension. | Jurdy, L., Merks, J. H., Pieters, B. R., Mourits, M. P., Kloos, R. J., Strackee, S. D., & Saeed, P. (2013). Orbital rhabdomyosarcomas: A review. Saudi journal of ophthalmology : official journal of the Saudi Ophthalmological Society, 27(3), 167–175. https://doi.org/10.1016/j.sjopt.2013.06.004

IRS post-surgical staging system:

  • Group I: localized disease, completely resected (excisional biopsy).
  • Group II: microscopic disease remaining after biopsy.
  • Group III: gross residual disease remaining after biopsy.
  • Group IV: distant metastasis present at onset.

Management

European pediatric Soft tissue sarcoma Study Group (EpSSG) protocol (EpSSG-RMS-2005):

  • Group I: chemotherapy consisting of VA.
  • Groups II and III: chemotherapy VA ± Ifosfamide ± rediotherapy
  • Group IV: Intensified chemotherapy regimen (IVA and doxorubicin) followed by one year of maintenance chemotherapy and radiotherapy

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