1. INTRODUCTION
Rhabdomyosarcoma is the most common soft tissue sarcoma in children,
with parameningeal tumors accounting for 15-20% of all
cases.1 Parameningeal rhabdomyosarcoma (PM-RMS)
specifically refers to those tumors arising from the nasopharynx, nasal
cavity, paranasal sinuses, parapharyngeal space, pterygopalantine fossa,
masticator space, mastoid cavity, and middle ear and are distinguished
anatomically and prognostically from the more favorable tumors arising
from the orbit and other head and neck sites.2Approximately 50% of patients with PM-RMS will present with lymph node
involvement and 25% with distant metastases.3Intracranial extension, skull base erosion, and cranial nerve palsy all
represent poor prognostic factors related to the local spread of
disease. Embryonal histology is the most common pathologic subtype,
representing approximately 70% of all parameningeal
tumors.4,5
Overall, the prognosis for PM-RMS is unfavorable, with a 10 year event
free survival of <65% and overall survival <70%
from pooled historical data.4 PM-RMS remains a
particularly challenging disease site to treat given its anatomical
location and predilection for local and leptomeningeal failure. Local
relapse results not only in severe loss of form and function in many
patients, but also an unacceptably high rate of mortality, with a 3-year
survival after local failure of <20%.6Given the locally advanced presentation of PM-RMS and the anatomical
constraints of the head and neck, gross total resection is usually not
feasible due to the risks of severe cosmetic and functional morbidity.
As such, definitive chemoradiation remains the preferred initial
treatment modality for PM-RMS, with surgery most commonly limited to an
initial biopsy to establish the diagnosis.
In this consensus review from the International Soft-Tissue Sarcoma
Consortium [INSTRuCT, consisting of the Children’s Oncology Group
(COG), European Pediatric Soft-Tissue Sarcoma Group (EpSSG), and
Cooperative Weichteilsarkom Studiengruppe (CWS)], we provide treatment
recommendations for the local management of PM-RMS.