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12 June 2013 - Case of the Week #276
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Thanks to Dr. Carolina Martinez Ciarpaglini, University Clinic Hospital of Valencia (Spain), for contributing this case and the discussion. To contribute a Case of the Week, follow the guidelines on our Case of the Week page.
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(6) We have updated the Skin-melanocytic tumor chapter based on reviews by Christopher Hale, M.D.
Case of the Week #276
An 11 year old boy presented with a left tonsillar mass present for three weeks. A biopsy was taken.
What is your diagnosis?
The tumor cells were immunoreactive for actin, desmin, myogenin and myoD1:
Left to right: actin, desmin, myogenin and myoD1 staining
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. Subtypes include embryonal-NOS, anaplastic, botryoid and spindle cell. Embryonal-NOS is the most common subtype (75%), usually affecting boys. It peaks at ages 0-4 years (US National Cancer Institute).
The tumor consists of dense zones of undifferentiated, differentiating and well differentiated cells. A cambium layer (cells immediately beneath the epithelium) is present. Undifferentiated cells are blue cells with minimal wispy cytoplasm but no skeletal differentiation, and central nuclei. Differentiating cells have moderate amphophilic or eosinophilic cytoplasm, often fibrillar. They may have a tadpole shape, often with nuclei arranged in tandem. Well differentiated cells have cytoplasmic cross-striations.
Tumors cells, as in this case, are immunoreactive for actin, desmin, myogenin and myoD1. There may occasionally be immunoreactivity for S100 and CAM5.2. The differential diagnosis consists of other small blue cell tumors, such as lymphoma and neuroblastoma. All children with rhabdomyosarcoma require multimodality therapy with systemic chemotherapy and either surgery or radiation therapy. Overall 5 year surival is over 80%, although it is much less for those with metastatic disease (eMedicine).
Nat Pernick, M.D., President
and Palak Thakore, Associate Medical Editor
30100 Telegraph Road, Suite 408
Bingham Farms, Michigan (USA) 48025
Alternate email: NatPernick@gmail.com