[Histological lesions of the bone marrow in medullary aplasia. Results of a common protocol on 261 biopsies].

In a cooperative study on bone marrow aplasia, 261 bone marrow biopsies have been examined in triple blind. 13 cases were excluded for technical defect, and 37 cases (17%) excluded for erroneous diagnosis (myelofibrosis or leukemia). It remains 176 first biopsies and 35 second biopsies (10th or 20th month). A quantitative depletion of the marrow was observed in 87% of the cases, but in 13 a rich marrow gave way to discuss the morphological definition of marrow aplasia. Framework lesions (reticulin, vessels, bone) and cytologic modifications (histiocytic or plasmocytic infiltrations) have been appreciated, and their importance in the induction of aplasia and in the prognosis is emphasized. Comparison between first and second biopsy has shown a repletion of the marrow in two third of the cases, the early unfavourable character of reticulinic lesions, and the favourable signification of plasmocytosis. A more complete comparison between marrow histology and other parameters of the study will improve the knowledge of physiopathology and prognosis of marrow aplasia.