8‐trisomy in the bone marrow. Report of two cases

The extra C chromosome in bone marrow mitoses from two patients with haematological disorders was identified as a number 8 by modified Giemsa staining followed by quinacrine mustard fluorescence. One of the patients had intermittent severe pancytopenia and the other mild granulocytopenia and thrombocytopenia. In spite of their differences in symptomatology, our attention was drawn to certain similarities, the most noticeable of which was ineffective erythropoiesis. From these results and a case report published by others it was concluded that all 3 patients with C‐trisomy of the bone marrow in whom the extra chromosome had been identified, had 8‐trisomy. Hence 8‐trisomy may account for a significant proportion of all bone marrow C‐tri‐somies, as is the case in congenital C‐trisomy. While 8‐trisomy is not necessarily a primary event in the aetiology of the malignant condition, it is possible that it gives the cells an advantage over other cells, and that this allows the trisomic cells to selectively populate the bone marrow. It may also lead to certain similarities in the clinical pictures, such as pronounced ineffectiveness of erythropoiesis.