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Case 109 - Discussion

Hematopathology Case



Desmin Myogenin
  • Tumor cells positive for t(2:13)(q35;q14) PAX3/FOXO1 by RT-PCR

  • Diagnosis: metastatic alveolar rhabdomyosarcoma

  • Notes: rhabdomyosarcoma (embryonal or alveolar) can closely mimic lymphoma. The metastatic tumor in the lymph node with no clinical history can be very challenging. Although rhabdomyosarcoma has a broad spectrum of morphology, the tumor cells usually appear more cohesive and pleomorphic than lymphoma cells; and the cytoplasm may be more abundant and denser. Nevertheless, it is always a good idea to perform desmin and myogenin immunostains on the unusual tumors after excluding other common ones, including poorly differentiated carcinoma, melanoma, and rare type of hematologic tumor. However, it is important to know that a substantial number of rhabdomyosarcoma cases can be positive for ALK1, which can also closely resemble ALCL morphologically .