Frequency of pseudo-Gaucher cells in diagnostic bone marrow biopsies from patients with Ph-positive chronic myeloid leukaemia.

Pseudo-Gaucher cells (PGC) are a characteristic finding in Ph-positive CML, and prolongation of survival was observed when PGC were detected within the bone marrow. However, the conspicuous variation in the reported frequencies indicates the necessity for analysis of their natural occurrence in the bone marrow from untreated CML patients. A total of 833 diagnostic bone marrow biopsies from patients with Ph-positive CML were examined for PGC by 7 observers. Proof of PGC was based on systematic examination of Giemsa-stained slides with and without polarization at high magnification. Birefringence within the cytoplasm turned out to be highly specific for PGC. The risk of overlooking PGC was at least 80% when the number of these storing histiocytes was 70 per slide or less, and at least 50% when the total amount per slide was < or = 250. This high risk of failure explained the disagreement among the authors. An intensive investigation by at least two observers is mandatory if results are to be evaluated in research. Under the conditions used in this study, the natural frequency of PGC within the bone marrow from untreated patients with a Ph-positive CML is much higher than assumed to date, amounting to about 70%. On the basis of these findings, the prognostic importance of PGC in CML must be evaluated critically.