It is one of the pediatric small round blue cell tumors, characterized by strong membrane expression of CD99 in a chain-mail pattern and negativity for lymphoid (CD45), rhabdomyosarcoma (myogenin, desmin, actin) and neuroblastoma (neurofilament protein) markers.
Flow cytometry (FCM) with CD45/CD56/CD81 and reverse transcriptase-polymerase chain reactions (RT-PCR) for tyrosine hydroxylase (TH) transcripts were used to evaluate neuroblastoma in bilateral BM aspirates at diagnosis, BM autografts, peripheral blood stem cell (PBSC) collections, and CD34(+) cell products of 27 children.
Using a panel of mononclonal antibodies, it was also possible to confirm the nature of the infiltration in paraffin sections and to differentiate it from other childhood small round cell tumors, especially neuroblastoma in paraffin sections (typical staining pattern: CD45-, CD43+, vW Factor, Ulex europeus I+, CD20-, CD45RO-, synaptophysin-, chromogranin-, cytokeratin-, desmin-).