K. F. Vykoupil

Chronic megakaryocytic granulocytic myelosis — CMGM

In 1,083 core biopsies of the bone marrow with myeloproliferative diseases 454 cases or 42% were found to have neoplastic megakaryopoiesis. Neoplasia of megakaryocytes was assumed from the conspicuous cytological atypicality revealed by light microscopy, extending and confirming earlier ultrastructural findings. Histopathology of the bone marrow in these patients was described as chronic megakaryocytic-granulocytic myelosis — CMGM — since neutrophilic granulopoiesis is also apparently neoplastic and both cell lineages showed a complete differentiation to mature forms. CMGM should be separated from the chronic granulocytic leukemia — CGL — which consists of only a single line proliferation. The incidence of CGL in our total of 1,083 patients was 25%. Both entities are included in chronic myeloid leukemia — CML — because of the demonstration of the Philadelphia chromosome in the hematopoietic cells of these two groups of patients. Primary or idiopathic thrombocythemia has to be differentiated from CMGM since there is no evidence for malignancy of the granulocytic series.

Hairy cell leukemia

In 24 patients with hairy cell leukemia, histological and fine structural findings from biopsies of the bone marrow are reported and their validity is compared with other diagnostic procedures available. Diagnosis by light microscopy of anterior iliac crest biopsies obtained by the method of myelotomy is possible with a high degree of accuracy. The differentiation of hairy cell leukemia from other myelo- or lymphoproliferative disorders based on cytomorphology as well as patterns of growth is emphasized. Morphological differences between fibrosis in this entity and other lesions such as malignant lymphomas, Hodgkins disease, osteomyelofibrosis and -sclerosis are emphasized. Electron microscopy of the bone marrow shows single fibroblastic cells with numerous slender cytoplasmic processes randomly dispersed among the hairy cells. These fibroblasts are probably responsible for the synthesis of the reticulin and collagen fibres in their surroundings. Moreover fine structure of the hairy cells demonstrates pinocytic activity but no apparent phagocytosis in contrast to the phagocytic reticulum cells (histiocytes, macrophages). In the bone marrow the precursor cells and the many immature forms of hairy cells exhibit an overall lymphocytoid appearance during their maturation, suggesting a lymphocytic origin.In 24 patients with hairy cell leukemia, histological and fine structural findings from biopsies of the bone marrow are reported and their validity is compared with other diagnostic procedures available. Diagnosis by light microscopy of anterior iliac crest biopsies obtained by the method of myelotomy is possible with a high degree of accuracy. The differentiation of hairy cell leukemia from other myelo- or lymphoproliferative disorders based on cytomorphology as well as patterns of growth is emphasized. Morphological differences between fibrosis in this entity and other lesions such as malignant lymphomas, Hodgkins disease, osteomyelofibrosis and -sclerosis are emphasized. Electron microscopy of the bone marrow shows single fibroblastic cells with numerous slender cytoplasmic processes randomly dispersed among the hairy cells. These fibroblasts are probably responsible for the synthesis of the reticulin and collagen fibres in their surroundings. Moreover fine structur of the hairy cells demonstrates pinocytic activity but no apparent phagocytosis in contrast to the phagocytic reticulum cells (histiocytes, macrophages). In the bone marrow the precursor cells and the many immature forms of hairy cells exhibit an overall lymphocytoid appearance during their maturation, suggesting a lymphocytic origin.

Chronic megakaryocytic-granulocytic myelosis — An electron microscopic study

The fine structure of the bone marrow in chronic megakaryocytic-granulocytic myelosis (CMGM) was studied in 5 nontreated patients to investigate possible malignant proliferation of megakaryocytes and the role of megakaryopoiesis in fibrillogenesis, terminating in osteomyelofibrosis. In comparison with normal megakaryopoiesis there is an enormous increase of the megakaryocytic cell line and many immature and atypical forms are seen. Most conspicuous are microforms, nuclear-cytoplasmic disorganization and nuclear inclusions. Asynchrony of maturation causes abnormal thrombocytogenesis with premature detachment of platelets resulting in immature and peculiar giant forms of thrombocytes. Besides megakaryocytes appearing superficially normal the maturation anarchy of many cells is so severe that by analogy with observations in other leukaemic cells these abnormalities are thought to be representative of a malignant growth. Moreover, there is a striking accumulation of microfibrils and single collagen fibres around megakaryoblasts. Since these cells contain all those organelles commonly associated with fibre production the initial step for fibrillogenesis may therefore arise from the megakaryoblasts prior to platelet release, or any fibroblast proliferation.

Myeloid dysplasia (MD): a hematological disorder preceding acute and chronic myeloid leukemia

Light- and electron microscopic appearances of core biopsies of the bone marrow in 27 selected patients out of about 195 cases with a clinically suspected preleukemic syndrome. The correct diagnosis of “ preleukemia” was established retrospectively by sequential biopsies of the iliac crest or autopsy in those patients who developed overt leukemia in periods ranging from 2 to 36 months. As a final diagnosis chronic myelogenous leukemia (CML) was established in 10, with accompanying blast crisis in 6 and acute non-lymphocytic leukemia (ANLL) in 11 cases. Histomorphology of the resin embedded cores of bone marrow showed hypercellularity in 21 specimens, a hypocellular marrow in 5 and a normal bone marrow in 1 case. There was also a conspicuous macrocytic or megaloblastoid maturation of erythropoiesis with frequent sideroblasts. Ultrastructural abnormalities included atypical nuclear clefts, dense iron deposits in the mitochondrial matrix and an increase of ferritin uptake. Neutrophilic granulopoiesis showed a shift to the left and often a remarkable aberration of nuclear segmentation consistent with a pseudo-Pelger-Huët anomaly. Electron microscopy displayed atypias of granulogenesis in comparison with maturation and segmentation of the nuclei, abnormal nuclear loops and blebs and very conspicuous nuclear fibrillar appendages (so called Nebenkerne). There was also an increase in eosinophilic granulocytes, monocytic elements, edema and a remarkable perivascular plasmacytosis of the myeloid stroma. Our results suggest that characteristic morphological features of the bone marrow exist before onset of overt, acute and chronic leukemia. These alterations are identical in CML and ANLL and are the morphological substrate of a maturation defect of hematopoiesis which precedes the establishment of the leukemic clone. The clinical term preleukemia should be replaced by myeloid dysplasia (MD), thus indicating transformation into overt leukemia in only a certain proportion of patients (only 27 of 195 clinically suspected patients who displayed an identical histopathology of MD in the bone marrow in 93 cases to date) and has to include ANLL as well as CML.

Ultrastructure of blastic crisis in osteomyelofibrosis

The clinical and morphological findings are presented in two patients suffering from myelofibrosis and osteomyelosclerosis which terminated in an acute blastic crisis. Clinical follow-up data and light microscopy of the bone marrow however, revealed a chronic megakaryocytic-granulocytic myelosis (CMGM) with progression into myelofibrosis during the course of disease. In one patient the blastic transformation involved predominantly basophils, and in the other, neutrophils, with an accompanying abnormal proliferation of megakaryocytes in both cases. Electron microscopy of this cell population demonstrated remarkable atypicalities of the neutrophilic, basophilic and megakaryocytic cell lines. These abnormalities consisted of a nuclear-cytoplasmic asynchrony and a partial arrest of maturation, sometimes resulting in bizarre cell forms. Our investigations support the hypothesis of a mixed cellularity type of myelosis with a gradual and insiduous progression into osteomyelofibrosis/-sclerosis and a potential blastic crisis. In the evolution of blastic crisis all cell lines may be transformed, but with predominance of one population — basophils and neutrophils in our two cases — in addition to atypicalities of megakaryocytes.