Rhabdomyosarcomas of the head and neck represent a large proportion (~40%) of all rhabdomyosarcomas and are the most common soft tissue sarcomas of the head and neck. For a general discussion of this tumor, please refer to rhabdomyosarcoma.
There are usually of the embryonal in cell subtype and are essentially only seen in children. They are classified by location into:
- orbital rhabdomyosarcoma: good prognosis (90% long term survival)
- para-meningeal rhabdomyosarcoma: worse prognosis (50% long term survival)
- other head and neck locations
Middle ear rhabdomyosarcomas are rare, accounting for only 7% of head and neck rhabdomyosarcomas. They typically present similarly to chronic otomastoiditis and are usually diagnosed too late for curative treatment. Frequently (30%) cranial nerve involvement is present at the time of diagnosis.
Histologically, rhabdomyosarcomas are low-grade small round blue cell tumors. Ewing sarcoma, neuroblastoma, and lymphoma share similar characteristics that make histopathologic differentiation of rhabdomyosarcoma hard.
Rhabdomyosarcomas resemble neuroblastomas in echotexture and often demonstrate low to medium echogenicity. With color Doppler, there is often variable internal vascularity.
- T1: isointense to slightly hyperintense
- T2: hyperintense
- T1 C+: marked contrast enhancement
- +/- intralesional hemorrhage or necrosis
As the differential diagnosis is vast, and the imaging findings are non-specific, it would be useful to describe in detail the:
- involvement of adjacent compartments
- perineural, vascular, and osseous involvement
- presence of lymphadenopathy
Treatment and prognosis
Treatment depends on the location and disease extent, with orbital and non-parameningeal head and neck locations having a better prognosis. Chemotherapy is first line for the treatment of rhabdomyosarcomas, with radiation therapy and surgery utilized for local tumor control.
The differential diagnosis for more superficial non-parameningeal locations includes:
The differential diagnosis for deeper parameningeal locations includes:
The sonographic differential also includes:
- 1. Schepper AM, Parizel PM, Vanhoenacker FM. Imaging of soft tissue tumors. Springer Verlag. (2006) ISBN:3540248099. Read it at Google Books - Find it at Amazon
- 2. Swartz JD, Loevner LA. Imaging of the Temporal Bone. Thieme Medical Pub. (2008) ISBN:1588903451. Read it at Google Books - Find it at Amazon
- 3. Bansal AG, Oudsema R, Masseaux JA, Rosenberg HK. US of Pediatric Superficial Masses of the Head and Neck. (2018) Radiographics : a review publication of the Radiological Society of North America, Inc. 38 (4): 1239-1263. doi:10.1148/rg.2018170165 - Pubmed