Refractory cytopenia with t(1;7),+8 abnormality and dysplastic eosinophils showing intranuclear Charcot-Leyden crystals: a fluorescence in situ hybridization study.

A case of refractory cytopenia and marrow eosinophilia showing t(1;7) translocation and concomitant trisomy 8 is reported. The eosinophils were dysplastic, and showed the unique feature of intranuclear Charcot-Leyden crystal formation, giving rise to a 'lip-like' appearance. We speculate that this unusual cytologic feature resulted from abnormal precipitation of Charcot-Leyden crystal protein in the eosinophils. By fluorescence in situ hybridization using a chromosome 8 specific alpha-satellite probe, the abnormal eosinophils were shown to have derived from the abnormal clone. We postulate that the dysplastic clone might have retained a differentiation potential and be responsive to normal haemopoietic stimuli.