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.