Blastic/blastoid transformation of follicular lymphoma - Immunohistologic and molecular analyses of five cases

Progression of follicular lymphoma to a higher-grade malignancy frequently heralds a Door prognosis; Clinical transformation is variably accompanied b y a spectrum of histologic changes characterized by alteration in growth an d cytology. Although several cytogenetic events and potential oncogenes hav e been documented in this progression, the underlying molecular mechanisms are largely unknown. We present five patients with an unusual histologic tr ansformation of follicular lymphoma manifested by blastic/blastoid morpholo gy,This transformation is histologically distinct from other types of trans formation of follicular lymphoma. All five cases exhibited the t(14;18) tra nslocation and expressed the BCL-2 protein. In addition, two of the five pa tients showed increased levels of the p53 protein within neoplastic cells i mplicating a possible role for this oncogene in blastic/blastoid transforma tion. The lack of BCL-1 and myeloid antigens by immunohistochemistry and fl ow cytometry studies served to distinguish blastic/blastoid transformation of follicular lymphoma from its morphologic mimics. This distinction is cli nically important because lymphoblastic and myeloid leukemias require signi ficantly differ ent therapeutic modalities and show better prognosis. Moreo ver, the lack of Epstein-Barr virus-specific mRNA suggests that this virus is unlikely to participate in blastic/blastoid transformation of follicular lymphoma.