Bone marrow morphology and CHIC2 FISH. The bone marrow biopsy (left panel) demonstrated hypercellularity and marked predominance of maturing neutrophilic granulocytes. Megakaryocytes were decreased, and no features of myelofibrosis or myelodysplasia were present. Notably, eosinophils and blasts were rare. By fluorescence in situ hybridization (right panel) using a tricolor probe set (Abbott Molecular), normal cells had two intact tricolor (green/orange/aqua) fusion signals whereas abnormal cells (90% in this sample) with monoallelic loss of CHIC2 (orange pseudocolor) had one green/aqua fusion signal.