Terminal deoxynucleotidyl transferase-positive lymphadenopathy in acute-phase chronic granulocytic leukemia.

A patient who had Philadelphia chromosome-positive chronic granulocytic leukemia had generalized lymphadenopathy. The lymph node biopsy revealed blast cells with small numbers of eosinophilic myelocytes indicative of granulocytic differentiation. In addition, the blast cells were found to have Philadelphia (Ph1) chromosome and extremely high levels of terminal deoxynucleotidyl transferase (TdT). The patient's peripheral blood and bone marrow reverted to the chronic phase, and the lymphadenopathy disappeared on two occasions with vincristine and prednisone therapy. The extramedullary proliferation of blastic chronic granulocytic leukemia, therefore, seems to share the histologic, cytogenetic biochemical, and chemotherapeutic sensitivity features of the basic disease process. TdT assay of enlarged lymph nodes in acute-phase chronic granulocytic leukemia might be used to identify the patients responsive to vincristine and prednisone despite the granulocytic histologic features of their lymph nodes.