Histologically, the PNET-like component showed morphological features akin to anaplastic medulloblastoma highlighted by widespread immunoreactivity for βIII-tubulin (TUBB3) and nonphosphorylated neurofilament protein, and to a lesser degree, Neu-N, synaptophysin, and CD99, whereas the gliomatous component was demarcated by glial fibrillary acidic protein (GFAP) labeling.
We obtained the final diagnosis of ES/PNET by immunohistochemical molecular study with positive staining for the MIC2 gene product (CD99) and a Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangement.
Herein, we describe a DSRCT in the maxilla of a young man, who was initially diagnosed with a primitive neuroectodermal tumor (PNET), based on histopathological appearance of a round cell tumor, with MIC2 and -FLI-1 positivity, on immunohistochemistry (IHC).
Based on the cytogenetic results and on the immunohistological investigation of MIC 2 expression, Ewing's sarcoma is suggested to be related closely to primitive neuroectodermal tumour.
We conclude that among the SRCTs, MIC2 expression is not limited to Ewing's sarcoma and primitive neuroectodermal tumors, but also shows strong and reliable expression in lymphoblastic lymphomas and related leukemias.