POSSIBILITIES AND LIMITATIONS OF CYTOCHEMICAL METHODS IN DIAGNOSIS OFACUTE-LEUKEMIA

Accurate identification and classification of leukemic blast cells is a very important prerequisite of the precise diagnosis of acute leukem ia and has a great impact on therapy and prognosis. The purpose of thi s review is to consider, in the broad sense of the word, the present p ossibilities and limitations of enzyme cytochemistry and to emphasize how cytochemistry may contribute, on integration with the other method s of study, to the final classification and differential diagnosis of acute leukemia, a highly variable hematological disorder. In this revi ew, the role of conventional enzyme cytochemistry, either dominant or subsidiary, in the discrimination of acute leukemia subtypes is discus sed. The survey confirms the absolute necessity of immunologic marker analysis in the accurate diagnosis of acute lymphoblastic leukemia, un differentiated or minimally differentiated leukemia and mixed-lineage leukemia because in these cases, the cytochemical evaluation provides insufficiently relevant information regarding blast cell origin, speci ficity of leukemia subtypes and the discrete stages of leukemic cell m aturation. On the other hand, cytochemical investigation is appreciate d to be dominant over immunophenotyping in characterizing acute myeloi d leukemia, because of the lack of specificity of the majority of immu nological markers against myeloid antigens and, because of the availab ility of standardized and sufficiently specific cytochemical reactions . The cytogenetic, molecular biological and electron microscopic studi es mentioned in this review supplement the important information for c orrect differential diagnosis of acute leukemia. The prognostic impact of enzyme cytochemistry in correlation to other methods is evaluated.