A total of 153 diagnostic bone marrow biopsies from patients with advanced stages of multiple myeloma corresponding to stages II and III according to the Durie/Salmon classification were evaluated prior to any treatment in a prospective therapy trial of the German Myeloma Treatment Group. Histologic sections were analyzed according to a pre‐defined system of criteria microscopically by 2 observers, determining three criteria: 1) grading by histopathology, regarding the cytologic differentiation of neoplastic cells and quantifying the percentage of plasmacytic, pleomorphic, and plasmablastic myeloma cells distributed within the sections; 2) the volume of infiltration; and 3) the pattern of neoplastic growth. Furthermore, four other criteria, namely hematopoiesis, fiber increase, osteomalacia, and micro‐osteo‐lesions, were evaluated. A cluster analysis using the three histological criteria revealed three groups of patients with significantly different survival times based on histological criteria only; the three criteria were mentioned above. It is concluded from these results that bone marrow biopsies, when evaluated histologically by grading and staging according to the three criteria, provide most valuable prognostic parameters in myeloma patients.

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To study chronic megakaryocytic-granulocytic myelosis, bone marrow biopsies from 5 patients were obtained. Ultrastructural quantitative and qualitative assessments demonstrate proliferation of both the megakaryocytic and granulocytic cell lines. Factors indicative of malignant growth in megakaryocytes included atypical maturation, nuclear-cytoplasmic asynchrony, nuclear inclusions and production of micromegakaryocytes. Abnormal thrombocyte delineation provoked giant platelet production. The neutrophil series also presented atypia as generally observed in chronic myelogenous leukemia. Even in cases without evidence of myelofibrosis under the light microscope, megakaryoblasts were associated with fibrillar structures. These cells may be responsible for the initial step in fibrillogenesis by providing a medium conductive to the collagen formation found in later stages of this disease.

Till present the advantages of methacrylate embedded bone biopsies for the diagnosis of haemoblastic disorders have been somewhat restricted. This was a result of the impossibility to apply histochemical methods and other sensitive staining procedures to semithin sections. A routine method is described whereby enzyme activity, excellent fixation and good sectioning ability are retained. Fixation is carried out using 4% purified formaldehyde buffered in 0.1M sodium cacodylate. Dehydration is done with a water-miscible glycolmethacrylate. Naphthol-AS-D-chloroacetate esterase activity can be observed in granules of the entire neutropil cell lineage. By use of this method it becomes possible to demonstrate acid phosphatase activity and immunoglobulins in atypical plasma cells of multiple myeloma. A considerable decrease in processing time, as well as a preservation of enzyme activity during the postal mailing of fixed tissue samples from outside are further advantages.