There are occasional cases of generalized myeloid hyperplasia and metaplasia which are not adequately described by the term myelogenous leukemia. Such cases are usually reported as aleukemic leukemia or aleukemic myelosis. In other groups of cases myeloid hyperplasia or metaplasia may be localized, forming single or multiple tumors within the bone marrow (multiple myeloma of the myeloid type) or extramedullary tumors (myeloblastomas). We wish to describe several instances of these less common forms of myeloid disease and to discuss their clinical recognition.
Table 1 presents the hematopoietic diseases appearing in the records of the University Hospital for a seventeen year period. The majority of the cases and all except one (case 3) of those reported in detail have been seen in the past eleven years and have been observed by one or by both of us. Necropsy and biopsy studies, for the most part, have been under the direction of