Two of the 25 (8%) undifferentiated neoplasms showed diffuse staining for PAX5, which indicated a B-cell derivation for these neoplasms that was not appreciated at the time of initial diagnosis.

All tissues were obtained under protocols approved by applicable IRBs and they were used for PAX5 staining. TMA paraffin sections were deparaffinized in xylene, rehydrated through graded ethanol ...