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7 March 2013 - Case of the Week #268
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Case of the Week #268
A 2 year old boy presented with a history of trauma 2 months previously. Ultrasound revealed a hematoma-like mass at the zygomatic bone, but one month later, the mass had enlarged to 7 cm. Excision revealed a 700 gram, 9 x 6 x 4.5 cm specimen of a nodular mass with parotid gland, 2 lymph nodes and a fragment of zygomatic bone.
What is your diagnosis?
Embryonal rhabdomyosarcoma is a primitive soft tissue sarcoma with small blue cells resembling embryonic skeletal muscle. It is the most common rhabdomyosarcoma (RMS) subtype (65% of RMS cases), and usually occurs in children ages 3-10 years in the head and neck (nasal and oral cavities, orbit, ear), prostate or paratesticular regions.
Gangliorhabdomyosarcoma is a rare variant of embryonal rhabdomyosarcoma which also has cells exhibiting neuronal differentiation (Histopathology 1986;10:181). A related entity is malignant ectomesenchymoma (Cancer 1987;59:1791, J Cancer Res Ther 2012;8:465), composed of a malignant mesenchymal component (often but not exclusively rhabdomyosarcoma) and a neuroectodermal component (often ganglion cells or neuroblasts).
The differential diagnosis includes Triton tumor (rhabdomyosarcoma plus MPNST), Wilms tumor and teratoma.
Optimal treatment is not well defined for this rare tumor, but most authors recommend a combination of surgery, radiotherapy, and a chemotherapeutic protocol based on the RMS component (Indian J Med Paediatr Oncol 2011;32:242).
Nat Pernick, M.D., President
and Palak Thakore, Associate Medical Editor
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