Definition, Clinical Features and Diagnosis of Myelofibrosis

Myelofibrosis and rapid thrombocytolysis. A case report

A 69-year-old woman was referred to our department because of moderate anemia and thrombocytopenia. On admission the spleen was slightly enlarged. On the basis of histological examination of biopsy specimens from spinal processes the diagnosis of myelofibrosis was made. The subsequent clinical course was progressively downhill. Although splenomegaly was of only moderate degree, severe anemia and thrombocytopenia supervened. Platelet mean life span was dramatically shortened (1.8 hours) and platelet production rate considerably increased (about 18xnormal). Neither corticosteroid therapy nor splenectomy alleviated the thrombocytopenia. Extremely large platelets, with diameters of up to 10 mum, were seen in the peripheral blood. The mean platelet diameter and percentage of megathrombocytes reached peak values about 2 weeks after splenectomy. It is suggested that the immunologic background of the rapid thrombocytolysis is similar to that which governs platelet destruction in idiopathic thrombocytopenic purpura.

Myelofibrosis associated with prominent periosteal bone apposition. Report of two cases

Myelofibrosis is a myeloproliferative disorder that is characterized by splenomegaly and bone marrow replacement by fibrous tissue. The predominant radiographic feature is osteosclerosis; however, in rare instances, periosteal bone apposition or periostitis is apparent in the metaphysis of the distal femura and proximal tibiae. It has been suggested that periostitis, when associated with fever and bone pain, is indicative of more aggressive disease. We report this unusual radiographic finding and its similar appearance to hypertrophic osteoarthropathy in two patients with myelofibrosis. In our patients, the presence of periosteal bone apposition did not correlate with increased disease aggressiveness.

Monocytic origin of fibroblasts: spontaneous transformation of blood monocytes into neo-fibroblastic structures in osteomyelosclerosis and Engelmann's disease

We describe here two pathological situations, osteomyelosclerosis and Engelmann's disease, in which HLA-DR blood monocytes modulate to the fibroblastic class, in long-term culture. Monocytes/macrophages were identified by immunofluorescence, using monoclonal antibodies against surface markers (Leu M3, CD 68, and HLA-DR) and the neo-fibroblasts by electron microscopy and immunofluorescence using monoclonal antibodies against a cytoplasmic enzyme specifically involved in the synthesis of collagen (5B5). Macrophages makers were found on the neo-fibroblasts, whereas HLA-DR macrophages expressed the cytoplasmic marker 5B5. Since osteoblasts are classically derived from fibroblasts, the significance of the in vitro differentiation of monocytes/macrophages into fibroblasts to the in vivo mechanism leading to excessive osteoblastic proliferation in both osteomyelosclerosis and Engelmann's disease, is discussed. The possible involvement of this pathway leading from monocytes to fibroblasts and osteoblasts in the normal process of bone modeling and remodeling in questioned.

Clinical significance of serum pro-collagen III in chronic myeloproliferative disorders

Pro-collagen III (PC III) has been proposed as a useful value for diagnosis and follow-up of myeloproliferative disorders. A significant difference is observed between polycythaemia vera (PV) and essential thrombocythaemias (ET) on one hand, and the pure erythrocytoses (PE) on the other hand, but a large overlap makes this test of low diagnostic value. High values are observed in primary and post-PV myelofibrosis, but excessive PC III levels in active PV are not predictive of evolution toward myelofibrosis. PC III level is lower in myelo-suppressed patients (32P, or hydroxy-urea) than in active cases or in patients treated by phlebotomies. We conclude that PC III measurement is of low diagnostic value for discriminating PV and PE, does not appear to allow short-term prediction of evolution to myelofibrosis, but may be useful to evaluate the role of treatment in delaying progression of PV toward myelofibrosis.

Immunohistochemical study of basement membrane proteins and type III procollagen in myelofibrosis

In this study the distribution of type IV collagen in the marrow is compared with that of laminin, another basement membrane protein. In addition, incompletely processed type III procollagen is identified with specific antibodies. In normal bone marrow the distribution of the type III procollagen antigen closely resembles that of reticulin staining. In all the myelofibrotic samples, representing both early and advanced disease, the fibrous tissue stains heavily for this antigen. Thus type III procollagen which has not completely lost its aminoterminal propeptide is a genuine component of the extracellular matrix fibres in human bone marrow. Laminin is found with type IV collagen in continuous basement membranes in arterial walls, whereas only discontinuous strips of staining are seen along the sinusoids in normal marrow. In myelofibrosis the dilated or obliterated sinusoids have thickened or continuous basement membranes, visible with both stainings. Neovascularization also increases the extent of basement membrane staining in fibrotic marrow. With respect of these antigens, there is no difference between primary and secondary myelofibrosis. These changes warrant the use of serum antigens related to type IV collagen and to type III procollagen as markers for developing myelofibrosis.

Type III aminoterminal propeptide of procollagen in some haematological malignancies

Marrow fibrosis is involved in some haematological malignancies. Either because of sampling errors, variations of focal distribution of fibrosis or the discomfort for patients of bone biopsies, conventional histology appears to be unsuitable for the follow-up of myelofibrosis. During collagen synthesis by marrow fibroblasts, the aminoterminal propeptide is removed from procollagen III and released in the serum. Thus, a sensitive radioimmunoassay of type III aminoterminal propeptide of procollagen (PC III) has been tested in myeloproliferative and lymphoproliferative disorders with a marked bone marrow fibrosis. In polycythaemia vera, PC III level was significantly increased as compared to controls and was related to marrow fibrosis of grade I. The more increased PC III values were observed in spent polycythaemia cases initially treated by phlebotomy alone. Follow-up showed a transformation into myeloid metaplasia. In contrast, PC III remained stable in patients treated with radiophosphorus 32P or hydroxyurea who did not transform. In myeloid metaplasia, results of PC III were significantly higher than in controls or polycythaemia vera cases. Myelofibrosis of recent onset (less than 2 years) gave higher values than chronic myelofibrosis. Increased PC III values were also emphasized in chronic myelocytic leukaemia, and in a few cases of refractory anaemia with excess of blasts, hairy cell leukaemia and chronic lymphocytic leukaemia.

Diagnostic value of bone marrow imaging with 111indium-transferrin and 99m technetium-colloids in myelofibrosis

111Indium--transferrin (111In) and 99mTechnetium-colloids (99mTc) bone marrow imaging of 55 myelofibrosis (MF) cases has been compared with clinical, histological, and iron-kinetics data. The best correlations are seen between the splenic uptake of 111In with the spleen/sacrum ratio of 59Fe at the first hour (r = 0.69, P less than 0.001) and also with the splenic erythropoiesis histologically assessed in ten splenectomized patients (r = 0.75, P less than 0.01). Moreover, sacrum uptake of 111In, when compared with sacrum uptake of 59Fe (r = 0.51, P less than 0.001) and with hematopoietic cellularity of the bone marrow (r = 0.57, P less than 0.001) reflects faithfully the hematopoietic cell content of the marrow. Thus, 111In bone marrow imaging provides a noninvasive and useful tool for the diagnosis of myeloid metaplasia in MF. Ferrokinetic studies still appreciate with better insight the amount of ineffective erythropoiesis or hemolysis and remains therefore of great value when splenectomy is discussed.

Platelet-associated IgG and IgM in myelofibrosis

Elevated levels of platelet-associated IgG and/or IgM were found in 15 of 18 patients with myelofibrosis (83%). All but 5 patients with elevated PAIg had active disease. The amounts of PAIg were not correlated to either S-Ig, platelet count or spleen size. Levels of PAIgG well above the normal range were especially found in patients with short duration of disease and/or a transitional myeloproliferative state. It is debated whether immune-mediated platelet dysfunction may be of importance for the development of bone marrow fibrosis, mediated by the release of platelet-derived growth factors in the bone marrow. Elevated PAIg may also contribute to abnormal haemostasis and thrombocytopenia in myelofibrosis.

Red cell aplasia in myelofibrosis with myeloid metaplasia. A distinct functional and clinical entity

Three patients with myelofibrosis with myeloid metaplasia are described. All three presented with grave anemia and red cell aplasia. Erythroid failure was the functional characteristic of erythropoiesis as resulted from erythrokinetic studies. Bone marrow was hypercellular or normocellular with hyperplasia of granuloblasts and megakaryocytes. Despite absent or mild splenomegaly at diagnosis, massive splenomegaly associated with a leukoerythroblastic blood film developed during the course of the disease. A relative young age (42-47 years), a subacute course of the disease and terminal blast crisis in two of them were the prominent clinical features of the patients. The differentiation from acute or malignant myelofibrosis is discussed. The patients appear to be a distinct subset within myelofibrosis with myeloid metaplasia.

Plasma fibronectin in myeloproliferative disorders and chronic granulocytic leukaemia

A significant reduction of plasma fibronectin levels was found in polycythaemia vera and myelofibrosis, the lowest levels being found in patients with marked splenomegaly. Plasma fibronectin concentration was normal in essential thrombocythaemia, and only modest reduction was seen in chronic granulocytic leukaemia in either controlled chronic phase or blast cell crisis. In a patient with myelofibrosis, the plasma fibronectin rose from less than 100 mg/l to 177 mg/l after splenectomy. Possible explanations include increased consumption of plasma fibronectin in the expanded mononuclear phagocyte system present in the liver and spleen, reduced hepatic synthesis, and the clearance of circulating immune complexes. Low plasma fibronectin concentrations may increase susceptibility to infection.

Acute myelofibrosis terminating in an acute lymphoblastic leukemia: a case report

A patient with acute myelofibrosis developed acute leukemia during the course of her disease. Light microscopic examination showed that the cells were lymphoblasts. The presence of terminal deoxynucleotidyl transferase and T- and B-lymphocyte markers suggested that the malignancy was of immature lymphoid cell origin. Terminal leukemic transformation in some cases of acute myelofibrosis may be of a lymphoid nature and, thus, less toxic chemotherapy could be used with a better prognosis.

Acute myelofibrosis in progressive systemic sclerosis. Report of a case developing during long term chlorambucil therapy and discussion of pathogenetic factors

A case of acute myelofibrosis occurring in the course of long-term chlorambucil therapy for cardiac manifestations of progressive systemic sclerosis (PSS) is reported. Although hematologic malignancies have been known to develop consequent to long-term use of alkylating agents, and bone marrow suppression is well known, acute myelofibrosis has not, to our knowledge, been reported as a complication of this therapy, nor has any specific myeloproliferative syndrome been described consequent to such therapy in a patient with PSS. As abnormal fibroblastic proliferation is central to both PSS and myelofibrosis, it may be speculated that the patient with scleroderma may be predisposed to this particular expression of hematologic dyscrasia. The roles of fibroblastic proliferation, and immunologic and vascular factors in these two illnesses are currently poorly understood.

Periostitis associated with myelofibrosis

Two patients with myelofibrosis developed fever, leg pain and periostitis. The first patient had myelofibrosis with myeloid metaplasia and was symptomatic for months before x-rays showed periosteal new bone formation in the lower extremities. He subsequently developed periostitis of both upper extremities. Radiation of the lower extremities resulted in significant pain relief. The second patient had a past history of polycythemia vera and experienced painful periostitis of the tibiae and fibulae. 99mTechnetium pyrophosphate bone scans showed increased uptake in the involved bones in both patients. Asymptomatic or painful periostitis may be related to the increased bone blood flow associated with myelofibrosis. Radiation can afford successful palliation in the severely symptomatic patient.

Acute ("malignant") myelosclerosis

This study is based upon an analysis of the hematologic and pathologic material from seven patients with acute myelosclerosis, as well as a review of the literature of 49 cases reported under this designation, or one of its synonyms. Patients with this disease characteristically present with pancytopenia, minimal or absent anisocytosis and poikilocytosis, and a fibrotic bone marrow showing hyperplasia and immaturity of all three cell lines, with particular prominence of megakaryocytes and their precursors. In addition, clinical splenomegaly is almost always absent, and the disease has a rapidly fatal course. We consider only one-fourth of the cases reported in the literature to have the clinical and hematologic features consistent with the diagnosis of acute myelosclerosis; the remainder represent a variety of myeloproliferative disorders, including chronic myelosclerosis with an accelerated terminal phase, acute myeloblastic leukemia with bone marrow fibrosis, myeloproliferative diseases that cannot be subclassified, and cases in which the data are insufficient for analysis. Using strict clinical and hematological criteria, acute myelosclerosis can be separated from other myeloproliferative disorders as a distinct clinicopathologic entity.

Erythroid hypoplasia in myelofibrosis: a feature associated with blastic transformation

Four cases of myelofibrosis have shown a pattern which is usually found only where there is erythroid hypoplasia and in none of these was there evidence of extramedullary erythropoiesis. Three of these cases terminated in a blastic phase. The findings suggest that the occurrence of erythroid hypoplasia in myelofibrosis may be associated with blastic transformation--whether as a predisposing factor or as a secondary event is still speculative. This phenomenon is discussed in relation to the natural history of myelofibrosis.