Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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March 14, 2019
ALVEOLAR PARAMENINGEAL RHABDOMYOSARCOMA
- Background
- Rhabdomyosarcoma, albeit rare in adults, is the most common soft-tissue sarcoma in children.
- Rhabdomyosarcoma of the head and neck can be categorized as parameningeal (originating in close anatomic relationship to the meninges), nonparameningeal, or orbital.
- Clinical Presentation
- Symptoms may include worsening headache over weeks with or without progressive diplopia.
- Sinus obstruction with mucopurulent or sanguineous discharge might commonly be seen in parameningeal subtypes.
- Key Diagnostic Features
- Erosion of the bony structures surrounding the homogenous mass on CT.
- Large, aggressive, heterogeneously hyperintense mass which may be centered in the nasopharynx or nasal cavity, middle ear or mastoid, paranasal sinuses, pterygopalatine or infratemporal fossae.
- Local invasion of the medial orbital wall may cause medial rectus and superior oblique muscles displacement, resulting in ipsilateral proptosis.
- In some cases alveolar rhabdomyosarcoma, serpentine flow voids might be observed.
- The PAX3-FOXO1, t(2;13), is a specific genetic translocation found only in alveolar rhabdomyosarcoma.
- Differential Diagnosis
- Olfactory Neuroblastoma: Some authors consider the separation from edematous brain parenchyma through peripheral cystic formations a differential sign for olfactory neuroblastoma, giving both diseases an almost identical imaging appearance. In our case, the imaging features were strongly suggestive of olfactory neuroblastoma, but for the PAX3-FOXO1, t(2;13), which is found only in alveolar rhabdomyosarcoma.
- Lymphoma: Can have an identical imaging appearance, typically presenting with prominent nonnecrotic lymph nodes.
- Nasopharyngeal Carcinoma: Usually more posteriorly located with prominent bony destruction and extension to the parapharyngeal and masticator spaces.
- Langerhans Cell Histiocytosis: Enhancing soft-tissue mass with characteristic beveled edge bony erosion.
- Treatment
- The primary tumor site, pathologic findings, and the clinical stage of the tumor play a significant roll in the management of the disease. Thus, the treatment plan should be made on an individual basis.
- For tumors that develop near the orbit, chemotherapy and radiation therapy might be considered.
- Following a histopathological diagnosis, the case was discussed at a multidisciplinary team meeting. Chemoradiotherapy was selected as the initial choice of treatment. After 3 months, the lesion showed a significant reduction of its size, prompting the possibility of surgical management.