Progressive myelofibrosis in agnogenic myeloid metaplasia

Progression of myelofibrosis in agnogenic myeloid metaplasia (AMM) has only rarely been documented because of the paucity of patients with sequential bone marrow examinations. At our institution, 27 patients with AMM underwent marrow examinations, separated by at least six months. Of the 20 patients who did not have maximal myelofibrosis shown by the original biopsy, 18 displayed temporal progression of the process; 11 of them had an increase of two or more grades using the Bauermeister scale. The grade remained constant in the remaining two patients. Several cases of a decreased degree of fibrosis or variation of grade in concomitant specimens showed that fibrosis may not proceed at an identical rate throughout the marrow and that the degree may vary with location.