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.     

Hepatic sinusoidal fibrosis in agnogenic myeloid metaplasia

Autopsy studies in two patients who had agnogenic myeloid metaplasia of long duration revealed significant extramedullary hematopoiesis in the liver associated with significant hepatic perisinusoidal/sinusoidal fibrosis. Fibrosis was nonzonal and irregularly distributed throughout the livers. Early changes were found in areas with normal parenchymal architecture and showed significant thickening of collagen fibers surrounding the liver cell plates. In areas with extensive fibrosis, coarse collagen fibers filled the sinusoidal space and resulted in the loss of hepatocytes, but nodular regeneration was absent. Hepatic perisinusoidal/sinusoidal fibrosis in livers with extensive extramedullary hematopoiesis may be more common than previously recognized.     

Fine-needle aspiration cytology of extramedullary hematopoiesis (myeloid metaplasia)

Myeloproliferative disease may be associated with extramedullary hematopoiesis (EH). Clinically, however, the differential diagnosis of solid masses in these patients includes not only EH but also inflammatory lesions and malignant neoplasms, including granulocytic sarcoma. We report the fine-needle aspiration (FNA) cytology of extramedullary hematopoiesis in five patients with a history of myeloproliferative disease. All of the masses developed subsequent to the diagnosis of myeloproliferative disease. Two of the patients had chronic myelogenous leukemia, one had essential thrombocythemia, and two had an unspecified chronic myeloproliferative disorder. The patients ranged in age from 50 to 88 years, and all presented with solid masses involving the kidney (two aspirates), liver (one aspirate), and lymph nodes (three aspirates). One of the lymph node aspirates was from a paratracheal lymph node. Cytologically, the lesions were composed of varying numbers of hematopoietic cells from all three hematologic cell lines. The Diff-Quik stain was especially helpful in the recognition of the hematopoietic cells such as granulocytic precursors, eosinophils, and megakaryocytes. In several cases, the megakaryocytic component was particularly prominent. In one case, the Factor VIII immunoperoxidase stain was used to confirm the megakaryocytic lineage of the multinucleated cells. The cytologic differential diagnosis, which includes granulocytic sarcoma, inflammatory disorders, and other lesions containing multinucleated giant cells, is discussed.     

Cytogenetics of agnogenic myeloid metaplasia: a study of 61 patients

Agnogenic myeloid metaplasia (AMM) or idiopathic myelofibrosis is a chronic myeloproliferative disorder characterized by fibrotic bone marrow, extramedullar haematopoiesis, and a leukoerythroblastic picture in circulating blood. The cytogenetic data on AMM are scanty and no recurring chromosome abnormality has been associated with the natural course of this disease. Trisomy 1q, del(13q), del(20q), and trisomy 8, appear in about two thirds of patients with demonstrable chromosome aberrations. We report on the cytogenetic analyses of 61 consecutive patients with AMM studied at diagnosis. The metaphases could not be found in 10/61 (16.4%) patients, and chromosome studies were successful in 51 patients. Twenty-one patients (41%) had an abnormal clone, whereas 30 (59%) patients had a normal karyotype. Most frequent pathological findings included trisomy 8 (either alone or within a complex karyotype) in five patients, aberrations of chromosome 12 (translocation in two, monosomy in two, and trisomy in one patient), and aberrations of chromosome 20 (interstitial deletion in two, monosomy in two, and trisomy in one patient). We also detected aberrations of chromosome 13 (translocation in two and an interstitial deletion and trisomy in one patient each) and chromosome 18 (derivative 18 in two patients and a monosomy and deletion in one patient each). Three patients exhibited complex aberrations involving several chromosomes, sometimes with a mosaicisam. A near-tetraploid karyotype was observed in a single patient. Balanced translocations [t(2;16)(q31;q24), t(5;13)(q13;q32), t(12;13)(p12;q13), and t(12;16)(q24;q24)] were present in four patients. While the series of patients studied displayed chromosomal aberrations that are frequently observed in AMM, we found some new abnormalities (balanced translocations and polyploidy) that are rarely observed in AMM.     

Autoimmune haemolytic anaemia as the presenting manifestation of agnogenic myeloid metaplasia

We report an unusual case of a 40-year-old female patient with a severe case of direct Coombs positive haemolytic anaemia, moderate hepatomegaly and marked splenomegaly. Her initial response to steroids was transient and was rapidly followed by a relapse. Therefore, she underwent splenectomy both as a therapeutic measure and to rule out an underlying lymphoproliferative disorder. Histopathological examination of the excised spleen, as well a liver biopsy, revealed extensive extramedullary haematopoiesis, while significant marrow fibrosis was noted in a trephine biopsy sample. These findings confirmed the concomitant diagnosis of agnogenic myeloid metaplasia with myelofibrosis.     

Ultrastructure of bone marrow tissue in so-called primary (idiopathic) myelofibrosis-osteomyelosclerosis (agnogenic myeloid metaplasia). II. The myeloid stroma (hematopoietic microenvironment)

An ultrastructural study was performed on bone marrow tissue in 8 patients revealing early and late stages of so-called primary (idiopathic) myelofibrosis - osteomyelosclerosis (agnogenic myeloid metaplasia) to evaluate the constituents of the hematopoietic microenvironment (myeloid stroma). A survey of the stroma cells disclosed an overall increase, particularly in so-called undifferentiated (primitive - pluripotent), but also in transitional (fibroblastic) reticular cells and myofibroblasts. The most primitive reticular cells were characterized by their stellate aspect with elongated slender cytoplasmic processes traversing the interstitial space, and by the scarcity of organelles. The transition into a fibroblast was preceded by the appearance of branching cisternal structures of the rough endoplasmic reticulum, extensively developed Golgi fields and an abundance in mitochondria. Frequently, so-called myofibroblasts were encountered displaying bundles of filaments along the subplasmalemmal region. Extracellularly fibrillar material with an irregular cross-banding as well as microfibrils could be observed. The many vascular structures (sinusoids and capillaries) exhibited a multilayered basement membrane-like material including many fibrils and adventitial cells (pericytes, smooth muscle and transitional reticular cells) with numerous cytoplasmic processes. Undifferentiated and transitional reticular cells as well as myofibroblasts seem to form an integral part of the hematopoietic microenvironment in OMF and are assumed to play an important role for the evolution of the disease-specific myelofibrosis in this disorder.     

Extramedullary hematopoiesis in a bronchial carcinoid tumor. An unusual complication of agnogenic myeloid metaplasia

A case of bronchial carcinoid tumor with foci of extramedullary hematopoiesis is presented. The patient had a 6-year history of agnogenic myeloid metaplasia and hepatosplenomegaly. All three hematopoietic cell lines were represented in different areas of the bronchial tumor. To our knowledge, this is the first case of extramedullary hematopoiesis described in a bronchial carcinoid and only the fourth report of hematopoietic cells in a neoplasm of otherwise unrelated origin. The pathogenesis of this uncommon finding is discussed and the literature is reviewed.     

Reversal of marrow fibrosis in agnogenic myeloid metaplasia by allogeneic peripheral blood stem cell transplantation

Agnogenic myeloid metaplasia (AMM) is a clonal hematopoietic stem cell disorder characterized by bone marrow fibrosis, extramedullary hemopoiesis, splenomegaly and a leukoerythroblastic blood picture. Current standard therapies using hydroxyurea, interferon, androgens or corticosteroids have not shown to prolong survival of patients with AMM. In this study, we performed a curative approach using an HLA-matched sibling as a donor for allogeneic peripheral blood stem cell transplantation (PBSCT) for a 45-year-old woman with AMM. Busulfan and cyclophosphamide were given as a conditioning regimen from day -7 to day -2 with cyclosporinA and methotrexate as post-transplant immunosuppressive therapy. Donor PBSCs were mobilized by G-CSF at 16 microg/kg/day for five days and transplantation was performed on March 2-3, 2000. The patient rapidly engrafted within 2 weeks after PBSC infusion without evidence of graft versus host disease. Her blood counts and bone marrow 2 years after transplantation were normal with full donor pattern by molecular analysis. In conclusion, marrow fibrosis can be reverted to normal by allogeneic PBSCT. Allogeneic PBSCT should thus be offered to AMM patients if an HLA-matched sibling is available. This report represents the first SCT for AMM in Thailand.     

Histomorphometry of bone marrow biopsies in primary osteomyelofibrosis/-sclerosis (agnogenic myeloid metaplasia) - correlations between clinical and morphological features

Summary Histomorphometry was performed on representative trephine biopsies of the bone marrow on admission of 50 patients (21 male, 29 female-age 67 years) with so-called primary osteomyelofibrosis/-sclerosis (OMF) not preceded by any other subtype of chronic myeloproliferative disorders. This study was firstly aimed at testing correlations between histological features (amount of haematopoiesis, cytological aspects of mega-karyocytes, density of reticulin and collagen fibres and degree of osteosclerosis) and laboratory data, as well as spleen size and duration of relevant prediagnostic symptoms. Secondly, we concentrated on a discrimination of OMF patients into two sub-groups according to bone marrow morphology and clinical variables. Statistical evaluation of histomorphometric variables and haematological findings disclosed that there was a progressive fibro-osteosclerotic process in the evolution of disease features. Increase in medullary fibrosis was significantly paralleled by an abnormal or pleomorphic megakaryopoiesis in the bone marrow: there was an increase in irregularity of perimeters for megakaryocytes and naked nuclei combined with smaller sizes of these elements including the nuclei. Additionally, there was a greater number of pycnotic bare nuclei. A number of morphometric features (density of fibres, degree of osteosclerosis, amount of haematopoiesis) were associated with corresponding clinical data (spleen size, length of preclinical history). By consideration of a set of basic histomorphometric variables our co-hort of 50 patients could be divided into an early hyperplastic subtype with no or minimal medullary reticulin and another group with conspicuous fibrotic and osteosclerotic alterations of the bone marrow. It was noticeable that we found no significant correlation between amount of haematopoiesis or marrow cellularity with splenomegaly. This result suggests that splenic haematopoiesis (myeloid metaplasia) may represent an autonomous or neoplastic process and not only compensation for a failing fibro-osteosclerotic bone marrow.Supported by a grant from the Deutsche Forschungsgemeinschaft (DFG-Th 390/1-1)     

Pro-megakaryoblasts in bone marrow tissue from patients with primary (idiopathic) osteo-myelofibrosis (agnogenic myeloid metaplasia). An immunomorphometric study on trephine biopsies

An immunomorphometric study was performed on bone marrow biopsies from 40 patients with primary osteomyelofibrosis--OMF, (agnogenic myeloid metaplasia) by employment of a monoclonal antibody against glycoprotein IIIa (Y2/51) to determine the number of pro-megakaryoblasts. Specimens from 15 individuals without any hematological disorder served as controls. With reference to the pertinent literature on megakaryocyte precursors and following a pilot study on corresponding smears, in tissue sections pro-megakaryoblasts were characterized by a size of 42.1 +/- 2.6 microns 2 (diameter 7.5 +/- 0.3 microns). In comparison with controls, in OMF no relevant increase in the number of pro-megakaryoblasts per square and cubic millimeter bone marrow was evaluable. The relative frequency of these precursors was significantly reduced due to an increase in the total amount of conspicuously large and abnormal megakaryocytes. Statistical analysis failed to reveal any correlations between counts for pro-megakaryoblasts or the total number of Y2/51--positive megakaryocytic elements with the density of argyrophilic fibers (determined by morphometry) or the platelet values. Our findings imply that in OMF the marked increase in circulating progenitor cells of the megakaryocyte lineage may be generated by extramedullary, probably splenic hematopoiesis. Moreover, the evolution of medullary fibrosis is thought to be associated with the striking predominance of large atypical, possibly overaged and hyperpolyploid megakaryocytes and not with an increase in precursor cells.     

Ultrastructure of bone marrow tissue in so-called primary (idiopathic) myelofibrosis-osteomyelosclerosis (agnogenic myeloid metaplasia). I. Abnormalities of megakaryopoiesis and thrombocytes

An electron microscopic study was conducted with the aim to analyze abnormalities of the megakaryopoiesis in bone marrow tissue of patients suffering from so-called primary (idiopathic) myelofibrosis-osteomyelosclerosis. In comparison with control specimens and in confirmation of light microscopical findings, a pronounced pleomorphism of the megakaryocytic cell line could be observed consisting of giant forms, micromegakaryocytes and naked (pyknotic) nuclei. Further atypias were expressed by a dissociation of nuclear-cytoplasmic maturation. These included particularly the amount of dense granules, and the development of the demarcation membrane system as well as the occurrence of emperipolesis (i.e. internalization of hematopoietic cells) already in immature or megakaryoblastic elements. In these specimens there was a striking variety in the appearance of dense granules of the alpha or bull's eye type revealing frequent elongated roll- and dumbbell-like shapes and a doubling of the nucleoids. Thrombocytes showed giant forms with either hypertrophy of the open canalicular system or abundance of dense granules and beta-glycogen accumulation. Remarkable was a focal sponge-like proliferation of the open canalicular system in many of the large platelets and giant and fused granules of the alpha and osmiophilic type. The abnormalities disclosed in megakaryo- and thrombocytes may have certain functional implications, i.e. to hemorrhage and thrombosis which are often encountered out of proportion to the platelet counts in this disorder. Moreover, those anomalies indicate a disorganization of megakaryopoiesis which may contribute to the abnormal release of factors (platelet-derived growth factor and factor 4) predominantly involved in the process of myelofibrosis.     

Detection of aberrant gene expression in CD34+ hematopoietic stem cells from patients with agnogenic myeloid metaplasia using oligonucleotide microarrays

Agnogenic myeloid metaplasia (AMM) is a clonal stem cell disorder that leads to ineffective hematopoiesis, bone marrow fibrosis, and extramedullary hematopoiesis. The molecular mechanisms underlying the development of this syndrome are currently unknown. Therefore, the aim of this study was to characterize aberrant gene expression in CD34+ hematopoietic stem cells from patients with AMM. We used oligonucleotide microarrays to analyze gene expression profiles in CD34+ hematopoietic stem cells from patients with AMM compared with expression in CD34+ cells from healthy individuals. We identified 95 highly differentially expressed genes (48 upregulated and 47 down-regulated) that are potentially involved in regulating abnormal hematopoietic proliferation and differentiation and confirmed many of them by quantitative polymerase chain reaction. Using class membership prediction analysis, we identified 75 genes whose expression profiles can accurately differentiate AMM samples from the controls. Using these 75 genes, we were able to discriminate patients with AMM from the controls by hierarchical clustering (Spearman's confidence correlation). The predictive power of these genes was verified by applying the algorithm to an unknown test set containing expression data from eight additional CD34+ samples (four AMM, four control). Our results indicate that a subset of genes may be used to differentiate patients with AMM from healthy individuals. Furthermore, we identify 95 genes whose aberrant expression may be involved in AMM.