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Two cases of Paget's disease of bone with radiographic manifestation of extramedullary hematopoiesis are described. While extramedullary hematopoiesis usually occurs as compensatory phenomenon in response to anemia, this was not the case in our patients. We believe pathologic fractures led to extrusion of hematopoietic marrow and resultant tumorous extramedullary hematopoiesis.
Extramedullary hematopoiesis presented as a diffuse mass causing almost complete obliteration of the spinal subarachnoid space in a patient with known agnogenic myeloid metaplasia. Pre- and post-radiation therapy films correlate well with significant clinical improvement in his neurological status.
Myelofibrosis (MF) is a chronic, progressive myeloproliferative neoplasm characterized by bone marrow fibrosis, ineffective blood cell production, and neoplastic extramedullary hematopoiesis (EMH) occurring primarily within the spleen. To explore the molecular mechanisms underlying splenic EMH, we performed single-cell transcriptional and chromatin profiling of cells from MF spleens that had been surgically removed. We demonstrate significant expansion of hematopoietic stem and progenitor cells, coupled with aberrant differentiation toward the erythroid and megakaryocytic lineages, associated with a significant enrichment of inflammatory pathways with enhanced NF-κB signaling and IFN responses, as well as dysregulation of the inferred function of differentiation-defining transcription factors. Finally, we report a significant remodeling of the immune microenvironment in MF spleens, characterized by emergence of dysfunctional T cell subsets and inflammatory memory B cells, suggesting the concomitant establishment of a pro-inflammatory and immune-tolerant tumor microenvironment within the spleen that influences hematopoietic cell differentiation and impairs tumor immune surveillance.
Extramedullary hematopoiesis (EMH) in the spinal epidural space is a rare but treatable cause of progressive paraparesis in patients with a variety of hematological and systemic disorders. We report a case of extensive thoracic epidural EMH causing progressive spastic paraparesis in a patient with agnogenic myeloid metaplasia. The literature describes 11 additional cases of myelopathy due to epidural EMH. All patients had EMH in the midthoracic region with elevated cerebrospinal fluid protein and abnormal spine roentgenograms or myelograms. Treatment with decompressive laminectomy, radiation therapy, or both, resulted in marked or complete recovery in 7 of 10 patients. Patients who develop paraparesis and who have a disorder associated with EMH should be evaluated rapidly for this treatable condition.
Three patients with carcinoma of the breast, extensive metastasis, and splenomegaly are described. Radioisotope studies with 59Fe and 51Cr revealed extramedullarly hematopoiesis and hemolysis. In addition to red cell hemolysis, ineffective erythropoiesis in the marrow and extramedullary sites contributed to the persistence of the anemic syndrome. Extramedullary hematopoiesis is not an effective compensatory mechanism in some patients with anemia and carcinoma of the breast.
A patient with beta-thalassemia intermedia with massive extramedullary hematopoiesis in the mediastinum is presented. These masses, which simulate tumors, are usually asymptomatic only rarely causing spinal cord compression. The histologic examination showed that they consist of hematopoietic tissue. The importance of correct diagnosis without surgery is stressed.
This study was undertaken to confirm or refute the findings of Naeye with regard to the pathologic continuation of extramedullary hematopoiesis in the livers of infants who die of the sudden infant death syndrome (SIDS). In general, our findings confirm his; however, although the data for SIDS do differ from those of controls, the differences are not statistically significant. Nevertheless, these results would seem to indicate the need for further investigation of the possibility of hypoxemia and/or anemia in affected infants.
A patient with an unusual myeloproliferative disorder, characterized by hepatosplenomegaly, myelofibrosis, ringed sideroblasts, and conversion to acute myeloblastic leukemia developed cardiac tamponade secondary to pericardia extramedullary hematopoiesis. Diagnostic criteria are discussed. Irradiation and systemic chemotherapy were successful in controlling the effusion.
A 63 year old man underwent lymphography because of anemia, splenomegaly, and fever. Nodes in the high para-aortic region had the appearance of involvement with malignant lymphoma. Subsequent biopsy showed that these changes were due to the partial replacement of nodal tissue with extramedullary hematopoiesis.
An immature neonate surviving for 45 minutes showed a generalized hydrops and hepatosplenomegaly unassociated with blood incompatibility. A marked activation of extramedullary haematopoiesis was observed not only in its liver and spleen, but also in the interstitium of the lungs, pancreas, kidneys, and adrenal glands. In addition, extensive necrosis of the brain and diffuse nonsuppurative myositis and myocarditis were found. All the changes were due to congenital toxoplasmosis, which has been confrimed by the findings of occasional pseudocysts within the placenta, by the result of the parasitologic examination of the brain of the autopsied infant and by serological examination of the mother post partum.
Nodular regenerative hyperplasia of the liver was identified at autopsy in a patient with myelofibrosis with extramedulary hematopoiesis, an association not previously reported. Portal venous hypertension, documented during the patient's terminal hospitalization, was ascribed, in part, to a high rate of blood flow through the enlarged spleen. Possible mechanisms accounting for the development of nodular regenerative hyperplasia of the liver, and evidence provided by this case pertinent to these mechanisms, are discussed.
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Splenomegaly is a defining feature of myelofibrosis, yet the contribution of splenic mesenchymal stroma to disease progression remains unclear. We combined spatial and single-nucleus transcriptomics of patient spleens with spatial and single-cell transcriptomics, as well as imaging analyses, of murine spleens to map extramedullary hematopoiesis niches. Activated red pulp reticular cells localize near hematopoietic stem and progenitor cells, and early disease is characterized by marginal zone disruption with lymphoid depletion preceding stromal remodeling. Trajectory analyses reveal a shift in reticular cells from hematopoiesis-supportive to inflammatory and pro-fibrotic states, driven by macrophage- and megakaryocyte-derived signals that activate complement and induce tumor necrosis factor α (TNF-α), transforming growth factor β (TGF-β), extracellular matrix, and Thbs1 programs. Non-hematopoietic complement component C3 deficiency or pharmacological C3 inhibition suppresses these pathways, restores splenic architecture, and reduces splenomegaly and bone marrow fibrosis. These findings identify complement-dependent stromal reprogramming as a mechanism governing hematopoietic niches and as a targetable axis in myelofibrosis.
Sequential hematologic studies were performed in four infants with malignant osteopetrosis who received prednisone. Prednisone therapy resulted in decreased liver and spleen size, decreased numbers of circulating immature blood cells, and increased hemoglobin concentration and platelet counts in all infants. The quantity and quality of hematopoietic tissue in bone marrow biopsies improved during prednisone therapy but showed no significant improvement without therapy. Sequential indium 111 chloride scans in one infant showed increased uptake in long bones and pelvis and decreased uptake in liver and spleen during therapy. We conclude that prednisone therapy of infantile osteopetrosis results in increased bone marrow hematopoiesis and decreased extramedullary hematopoiesis.
Agnogenic myeloid metaplasia, one of the entities in the myeloproliferative syndrome, usually initially appears with splenomegaly, hepatomegaly, and a normocytic, normochromic anemia. Extramedullary hematopoiesis is also a common finding, but is exceedingly rare in the major salivary glands. We report a case of extramedullary hematopoiesis in the parotid gland and discuss the differential diagnosis and characteristics of the disease.
Extramedullary hematopoiesis was detected in routine sections of spleen and liver from two patients with thrombotic thrombocytopenic purpura (TTP). In patients with other types of hemolytic anemia and in normal persons, extramedullary hematopoiesis was not found in spleen or liver. The results of this study raise the possibility that TTP may fit within the myeloproliferative category, perhaps representing an acute variant of Di-Guglielmo Syndrome.
Muscle biopsy specimens of 20 full-term neonates (13 surgical and seven necropsy specimens) with clinical evidence of neuromuscular disease were studied to determine the diagnostic usefulness of this procedure in the newborn. Characteristic pathologic alterations were identified in specific diseases. Some findings were similar to those seen later in life, but others differed from those expected in the same diseases at older ages. Persistence of fetal muscle cells was a characteristic common to several congenital myopathies and neuropathies. Lymphocytic infiltrates, muscle fiber necrosis, and architectural alterations of the muscle fibers were not seen at birth. Extramedullary hematopoiesis may involve newborn muscle. Muscle biopsy is a safe and simple procedure in the neonatal period and has a diagnostic reliability as good as at older ages, but histochemistry and sometimes electron microscopy are essential supplements to classical histology for interpretation. Recommended indications for muscle biopsy in the neonatal period are multiple joint contractures at birth or hypotonia and weakness, of unknown origin.
The evolution of the disease process in 92 patients with non-Hodgkin's lymphoma has been analyzed by comparing the initial histopathologic material with that obtained at autopsy. The distribution of lymphoma did not differ substantially among the subtypes, but the gross appearance of the lesions was different among certain subtypes, particularly between the "small cell" and "large cell" types. The diffuse lymphomas showed a remarkable constancy of subtype in the same patient, whereas the nodular lymphomas showed a high frequency of change to a diffuse pattern and/or a larger cell type. Diffuse histiocytic lymphomas with plasmacytoid features showed a striking propensity for involvement of the gastrointestinal tract. The occurrence and significance of bizarre pleomorphic giant cells, epithelioid histiocytes, a "starry-sky" pattern, erythrophagocytosis, hemosiderosis and extramedullary hematopoiesis are reported. All patients received anti-lymphomatous chemotherapy and/or radiotherapy. A second malignancy was observed in 8 patients. Thirteen patients showed no residual lymphoma at autopsy. The cause of death was considered to be related to lymphoma in all 92 patients; 67 had infections identified.