Power of the MAC (morphology-antibody-chromosomes) method in distinguishing reactive and clonal cells: report of a patient with acute lymphatic leukemia, eosinophilia, and t(5;14).

We present a patient with acute lymphatic leukemia, eosinophilia, and a 5;14-translocation, a rare but well-documented condition. In order to clarify whether granulocytes were involved in the disease, we applied the MAC (Morphology-Antibody-Chromosomes) technique to samples of the bone marrow and, during a central nervous system relapse, to those of the cerebrospinal fluid. The karyotype of the blast cells was 47,XY, + X,t(5;14)(q31;q32),i(7)(q10). Interphase cytogenetic study by in situ hybridization with an X-specific alphoid probe revealed the abnormality in CD10, CD19, and TdT (terminal deoxynucleotidyl transferase) positive lymphoid cells, whereas CD13 positive, Sudan black B positive, eosinophilic, and basophilic granulocytes as well as monocytes and small lymphocytes did not have the abnormality. Our results show that the eosinophilic and basophilic granulocytes in this subtype of acute leukemia do not belong to the malignant clone but are reactive. This study also confirmed the usefulness of the MAC technique in distinguishing neoplastic and reactive cells in malignancy.