Cytochemical studies in the blastic transformation of chronic granulocytic leukaemia.

The cytochemical features of blast cells were studied in 45 patients with blastic phase of chronic granulocytic leukaemia. Various degrees of Sudan black B positivity was characteristic of myeloblastic transformation (23 patients), while in the medullary blast cells of nine patients with myelomonocytic transformation the alpha-naphthyl-acetate esterase showed intensive activity. In two cases the demonstrability of beta-thromboglobulin and factor VIII-related antigen in blast cells showing otherwise PAS, acid phosphatase and alpha-naphthyl-acetate esterase activity referred to megakaryocytic transformation. In six patients with lymphoid blast crisis proliferation of the Sudan negative blast cells with different granular PAS, acid phosphatase and/or beta-glucuronidase positivity was demonstrated. In five cases the cytochemical findings of leukaemic cells indicated biphenotypic and mixed transformation, respectively.