Myocardial extramedullary hematopoiesis following myocardial infarction

Extramedullary hematopoiesis (EMH) usually accompanies a chronic hematologic disease in adults or prematurity in neonates. We observed a striking case of EMH in the explanted heart of a 13-year-old boy who underwent transplantation after extensive myocardial infarction. The florid myeloid proliferation raised the possibility of a leukemic process. To our knowledge, extensive myocardial EMH subsequent to myocardial infarction has not been previously reported. Possible mechanisms underlying EMH in the myocardium are presented.     

Primary cytodiagnosis of peritoneal extramedullary hematopoiesis

Cytologic examination of peritoneal fluid in a patient with known myelofibrosis and previous splenectomy revealed megakaryocytes along with erythroid and myeloid precursors. These findings were consistent with extramedullary hematopoietic (EMH) implants of the peritoneum. A few similar cases have been occasionally reported in the literature. This case represents an additional example of a primary diagnosis of peritoneal EMH in which therapy was based on the cytologic findings and sequential cytologic observations were made.     

Diabetes insipidus caused by extramedullary hematopoiesis

Myeloid metaplasia involving the central nervous system is a rare occurrence most frequently found as an incidental finding at autopsy. A case is presented of a 56-year-old man with myeloid metaplasia and myelofibrosis, who developed diabetes insipidus. Postmortem examination revealed posterior pituitary involvement by extramedullary hematopoiesis with fibrosis and gliosis. Diabetes insipidus caused by extramedullary hematopoiesis is a rare event and is thus noteworthy.     

Pleural mass forming extramedullary hematopoiesis masquerading as a malignant neoplasm

Extramedullary hematopoiesis (EMH) represents the presence of immature hematopoietic elements and their differentiation into mature blood components outside of the medullary bone and may be seen in a variety of circumstances in the postnatal period, but is most strongly associated with disorders of the hematopoietic system. Postnatally, EMH is typically identified at sites of fetal hematopoiesis, the spleen, and liver, but occasional reports have identified it in nearly every tissue of the body. We report a case of EMH presenting as pleural mass, initially suspected to represent a neoplastic process in a patient with multiple comorbidities, including history of carcinoma, but without co‐existing hematologic disorder. On‐site evaluation of the fine‐needle aspiration specimen was initially suspicious for a malignant neoplasm, but further evaluation revealed the lesion to be a mass forming focus of non‐hepatosplenic EMH. In the era of increasing utilization of imaging, mass forming EMH is increasingly detected. When unsuspected, EMH may present a diagnostic challenge for the pathologist and may be confused for a neoplastic process. Diagn. Cytopathol. 2015;43:996–999. © 2015 Wiley Periodicals, Inc.     

Bronchial extramedullary hematopoiesis preceding chronic myelogenous leukemia

Extramedullary hematopoiesis of the bronchus is rare. The case of a 72-year-old man in whom the right lower lobe bronchus was obstructed by extramedullary hematopoiesis is presented. Ten months after the initial presentation, Philadelphia chromosome-negative chronic myelogenous leukemia was diagnosed. Such findings have not been reported previously. The various anatomic locations of extramedullary hematopoiesis are reviewed, with an emphasis on intrathoracic and pulmonary presentations. The clinical and pathologic features and the differential diagnosis in the present case are discussed.     

Pseudo-Gaucher cells in peritoneal fluid: an uncommon manifestation of extramedullary hematopoiesis.

Pseudo-Gaucher cells have been observed in the bone marrow of patients suffering from a variety of hematologic disorders, including chronic myeloid leukemia, multiple myeloma, and immune thrombocytopenic purpura, as well as other conditions, such as rheumatoid arthritis. While the presence and potential clinical significance of pseudo-Gaucher cells have been documented in the hematology literature, references in standard cytology texts and journals are lacking. We report a case of ascites developing in the context of myelofibrosis, in which abdominal paracentesis yielded numerous pseudo-Gaucher cells as part of a mixed cellular population containing immature hematopoietic elements, consistent with extramedullary hematopoiesis.     

Synovial tumefactive extramedullary hematopoiesis associated to polycythemia vera

The case of a 66-year-old male patient with a chronic myeloproliferative type polycythemia vera disorder, who after 2 years of evolution is developing a tumefactive extramedullary hematopoiesis (TEH) located in the synovial of the articulation in the right knee, is described. The tumor histologically consists of a relatively lax and edematous synovial structure diffusely infiltrated by mature and semimature hematopoietic cellular population. The simultaneous study of the bone marrow reveals medullar spaces full of hematopoietic cellularity, with a predominance of megakaryocytic and red series, and with the addition of severe reticulin fibrosis, facts that suggest a progression toward myelofibrosis. The TEH developed in tissues without a reticulum endothelial system is very uncommon. We provide data about the first case located in the synovial membrane and we review the literature regarding this pathologic entity.     

Mass-forming extramedullary hematopoiesis diagnosed by fine-needle aspiration cytology

Extramedullary hematopoiesis (EMH) is usually a microscopic finding. However, it may present as a mass-forming lesion making it amenable to fine-needle aspiration biopsy (FNAB). When mass-forming EMH occurs, it can simulate a neoplasm clinically and radiologically. Additionally, the megakaryocytes can mimic malignant neoplastic cells, particularly if EMH is not a considered diagnosis. We report six cases of mass-forming EMH diagnosed by FNAB and evaluate the utility of FNAB in diagnosing EMH. Four patients had prior diagnoses of hematologic disorders, one patient had malignant mastocytosis who presented with lymphadenopathy and one patient had a history of carcinoma. The patients' ages ranged from 46 to 78 yr with an equal sex distribution. Aspirate smears showed trilineage hematopoiesis. The cytomorphologic differential diagnosis included metastatic carcinoma, Hodgkin lymphoma and myeloid sarcoma. No special stains were necessary due to the classic cytologic findings and prior hematologic history.     

Alveolar airspace and pulmonary artery involvement by extramedullary hematopoiesis: a unique manifestation of myelofibrosis

Pulmonary extramedullary hematopoiesis is a rare manifestation of myelofibrosis. We encountered a unique case of pulmonary extramedullary hematopoiesis occurring in a 59-year-old white man, where in addition to the typical foci of interstitial hematopoietic cells, a surgical lung biopsy showed airspace and arterial wall involvement. Airspace foci were associated with acute and organizing alveolar hemorrhage, while within arteries the hematopoietic elements had a striking predilection for the vascular intima. The hematopoietic foci included erythroid precursors, myeloid precursors, and megakaryocytes, which were immunoreactive with hemoglobin, myeloperoxidase, and CD61, respectively. Whether extramedullary hematopoiesis represents in situ embryonic stem cell differentiation or a compensatory seeding of hematopoietic cells from the bone marrow remains to be elucidated. However, familiarity with these findings in the lung could be helpful in uncovering occult hematological disorders accompanied by extramedullary hematopoiesis. Extramedullary hematopoiesis should also be considered as a cause of pulmonary hemorrhage, especially in the setting of myelofibrosis.     

Chronic idiopathic myelofibrosis presenting as cauda equina compression due to extramedullary hematopoiesis: a case report

Extramedullary hematopoiesis (EMH) is occasionally reported in idiopathic myelofibrosis and is generally found in the liver, spleen, and lymph nodes several years after diagnosis. Myelofibrosis presenting as spinal cord compression, resulting from EMH tissue is very rare. A 39-yr-old man presented with back pain, subjective weakness and numbness in both legs. Sagittal magnetic resonance imaging showed multiple anterior epidural mass extending from L4 to S1 with compression of cauda equina and nerve root. The patient underwent gross total removal of the mass via L4, 5, and S1 laminectomy. Histological analysis showed islands of myelopoietic cells surrounded by fatty tissue, consistent with EMH, and bone marrow biopsy performed after surgery revealed hypercellular marrow and megakaryocytic hyperplasia and focal fibrosis. The final diagnosis was chronic idiopathic myelofibrosis leading to EMH in the lumbar spinal canal. Since there were no abnormal hematological findings except mild myelofibrosis, additional treatment such as radiothepary was not administered postoperatively for fear of radiotoxicity. On 6 month follow- up examination, the patient remained clinically stable without recurrence. This is the first case of chronic idiopathic myelofibrosis due to EMH tissue in the lumbar spinal canal in Korea.     

Hermansky-Pudlak syndrome: a clinicopathologic study

The Hermansky-Pudlak syndrome is a rare disease characterized by multisystemic involvement. Seven families with the disorder were identified in the Puerto Rican population of one municipal hospital, suggesting that the incidence in the Puerto Rican community is sufficient to warrant both dissemination of information about the disease and further investigation. The present study was an attempt to achieve both of these goals.     

Cardiac rhabdomyoma: a clinicopathologic study

We studied the clinical and pathologic features of 17 cardiac rhabdomyomas from 13 males and four females whose ages ranged from birth to 9 yr (mean, 36 wk). Eleven were multiple, and tumors were found throughout the heart. Four patients had congenital heart disease, and three had tuberous sclerosis; of the ten sporadic cases, four were surgical resections. Three of the four patients with surgical resections survived postoperatively. Two patients presented with sudden cardiac death. Immunohistochemical stains on seven tumor revealed diffuse positivity for myoglobin, actin, desmin, and vimentin, with negative results for S-100 protein, similar to adjacent cardiac muscle. We conclude that cardiac rhabdomyomas can be sporadic, can be associated with tuberous sclerosis, or can be seen with other cardiac malformations. They usually present early in life with a variety of symptoms, including sudden death, and attempts at resection may be successful.     

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.     

An etiologic model proposing that sporadic adult-onset carcinoma is extramedullary hematopoiesis

This model proposes that primary carcinomatous tumors and almost all metastases are extramedullary hematopoietic tissue formed to compensate for reduced hematopoietic activity in the bone marrow. These marrow lesions are currently considered to be metastatic in origin, but as fibrosis and sclerosis are identifying features they are here equated to myelofibrosis. Myelofibrotic marrow is characterized by an increase in the number and size of vascular sinusoids. The increased blood flow suggested by this morphology, and observed in myelofibrosis patients, causes a rise in marrow pressure which may trigger the fibrosis. Specific carcinoma morphologies are equated to stages in endochondral bone and marrow formation and, as such, cancer cell identity varies with morphology. For example, infiltrating carcinomas of the breast consist of collagen and mucoid secreting cells in single file formation. This morphology is equated to the cartilagenous stage of marrow formation, when mesenchymal stem cells proliferate and differentiate into chondroblasts. In this model "infiltrating" cells arise in situ from stem cells located in the connective tissue. Tubular breast carcinoma, with its single layer of osteoblast-like carcinoma cells encircling small lumens and long branching tubules, is equated to the trabecular stage of marrow formation during which osteoblasts surround small pieces of calcified cartilage and begin secreting osteoid that will form the trabeculae. Lobular carcinoma in situ consists of cancer cell clusters separated by narrow clear spaces that, under high magnification, appear vascular. This morphology is equated to hematopoietic tissue in which primitive hematopoietic cells lie between anastomosing sinusoids. Similar cartilagenous, trabecular and hematopoietic morphologies can be found in carcinomatous tumors of most organs, but the nomenclature is variable. The hematopoietic carcinomas share numerous features with hematopoietic tissue including a structure composed of intermingled normoxic and hypoxic regions and a metabolism characterized by elevated levels of glycolysis. They also contain similar proportions of clonal cells. If this model is correct it necessitates a change in the treatment of carcinoma. If cancer cells are not the enemy, but desperately needed immature blood cells, and the medical problem is not the presence of tumors, but the inefficiency of this extramedullary hematopoietic tissue, then treatment should focus on increasing marrow hematopoiesis. As evidence suggests that the marrow lesion is the result of increased hydrostatic pressure this could be done by reducing blood volume. One way to accomplish this may be through the ingestion of ephedrine, as it is hypothesized to increase vascular tone.     

Sustained exposure to nicotine leads to extramedullary hematopoiesis in the spleen

The effect of sustained exposure to nicotine, a major constituent of cigarette smoke, on hematopoiesis in the bone marrow (BM) and spleen was evaluated in a murine model. BALB/c mice were exposed to nicotine subcutaneously using 21-day slow-release pellets. Exposure to nicotine had no effect on the proliferation of long-term BM cultures or on their ability to form colonies. However, there was a significant decrease in the generation of lineage-specific progenitor cells, specifically eosinophil (colony-forming unit [CFU]-Eos) progenitors, in the BM of nicotine-exposed mice compared with control mice. Surprisingly, sustained exposure of mice to nicotine was found to induce significant hematopoiesis in the spleen. There was a significant increase in total colony formation as well as eosinophil-, granulocyte-macrophage-, and B-lymphocyte-specific progenitors (CFU-Eos, CFU-GM, and CFU-B, respectively) in nicotine-exposed mice but not in control mice. Sustained exposure to nicotine was associated with significant inhibition of rolling and migration of enriched hematopoietic stem/progenitor cells (HSPCs) across BM endothelial cells (BMECs) in vitro as well as decreased expression of beta2 integrin on the surface of these cells. Although sustained exposure to nicotine has only a modest effect on BM hematopoiesis, our studies indicate that it significantly induces extramedullary hematopoiesis in the spleen. Decreased interaction of nicotine-exposed HSPCs with BMECs (i.e., rolling and migration) may result in altered BM homing of these cells, leading to their seeding and proliferation at extramedullary sites such as the spleen.     

Changes in histidine decarboxylase expression influence extramedullary hematopoiesis in postnatal mice

Histidine decarboxylase (HDC), histamine synthase, is expressed in hematopoietic stem cells and in lineage-committed progenitors in the bone marrow (BM). However, the role of histamine in hematopoiesis is not well described. To evaluate the role of histamine in hematopoiesis, we analyzed the changes in HDC expression at hematopoietic sites, the BM, spleen, and liver of 2-, 3-, and 6-week-old wild-type mice. We also performed morphological analyses of the hematopoietic sites using HDC-deficient (HDC-KO) mice. In wild-type adults, HDC expression in the BM was higher than that in the spleen and liver and showed an age-dependent increase. Histological analysis showed no significant change in the adult BM and spleen of HDC-KO mice compared to wild-type mice. In the liver, HDC expression was temporarily increased at 3 weeks and decreased at 6 weeks of age. Morphological analysis of the liver revealed more numerous hematopoietic colonies and megakaryocytes in HDC-KO mice compared to wild-type mice at 2 and 3 weeks of age, whereas no changes were observed in adults. Most of these hematopoietic colonies consisted of B220-positive B-lymphocytes and TER119-positive erythroblasts and were positive for the cell proliferation marker PCNA. Notably, these hematopoietic colonies declined in HDC-KO mice upon N-acetyl histamine treatment. A significant increase in the expression of hematopoiesis-related cytokines, Il3, Il7, Epo, Gcsf, and Cxcl12 mRNA was observed in the liver of 3-week-old HDC-KO mice compared to wild-type mice. These results suggest that histamine-deficiency may maintain an microenvironment suitable for hematopoiesis by regulating hematopoiesis-related cytokine expression in the liver of postnatal mice.     

Pleural fluid extramedullary hematopoiesis case report with review of the literature

Extramedullary hematopoiesis (EMH) is the trilineage formation of normal blood cells outside of the bone marrow. While predominantly seen in the spleen and liver, EMH rarely occurs in serous effusions. Accurate diagnosis requires recognition of megakaryocytes and other precursor hematopoietic elements. We present a case of pleural fluid EMH in a patient with primary myelofibrosis and developing leukemia, with a review of the literature, prognostic implications and diagnostic challenges. Diagn. Cytopathol. 2016;44:41–44. © 2015 Wiley Periodicals, Inc.     

Oncogenic osteomalacia: a clinicopathologic study of 17 bone lesions.

Oncogenic osteomalacia is an unusual and rare clinicopathologic syndrome characterized by mesenchymal tumors that apparently produce osteomalacia and biochemical abnormalities consisting of hypophosphatemia, normocalcemia, and increased levels of alkaline phosphatase. We collected from the Mayo Clinic files and from our consultation files the records for 17 cases of osteomalacia associated with bone lesions. There were five cases of fibrous dysplasia, three of hemangiopericytoma, and two of phosphaturic mesenchymal tumor. There was one case each of osteosarcoma, chondroblastoma, chondromyxoid fibroma, malignant fibrous histiocytoma, giant cell tumor, metaphyseal fibrous defect, and hemangioma. In this study we can figure out that the most common characteristic histologic features of our cases were hemangiopericytomatous vascular proliferation, fine lace-like stromal calcification, and stromal giant cells. In most of the cases, the clinical and biochemical symptoms and signs resolved soon after complete resection of the lesion. When the lesion recurred or metastasized, the symptoms and signs also recurred.