Detection of residual leukemic blasts in adult patients with acute T-lymphoblastic leukemia using bone marrow trephine biopsies: comparison of fluorescent immunohistochemistry with conventional cytologic and flow-cytometric analysis.

Evaluation of remission in adult acute lymphoblastic leukemia (ALL) normally relies on cytologic evaluation and flow-cytometric analysis. The diagnostic impact of bone marrow trephine biopsies has not been studied so far. We investigated 26 biopsies of 16 patients with T-ALL. Double fluorescent immunostaining with TdT and CD3 was performed. Corresponding cytologic evaluation and flow-cytometric data were available. In 17 of 26 investigations, the results were concordant (either positive or negative). In one examination, residual blasts were not recognized by trephine biopsy, but by other methods. By contrast, in eight investigations, the leukemic blasts were found only in the bone marrow trephine biopsies. Regarding the evaluation of remission of T-ALL, in our retrospective study, bone marrow trephine biopsies with double immunostaining were found to be sensitive and specific for the detection of residual blasts. This method may add to the conventional cytology and flow-cytometric analysis.