Nonhepatosplenic extramedullary hematopoiesis: associated diseases, pathology, clinical course, and treatment

Primary myelofibrosis: 2014 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by stem cell-derived clonal myeloproliferation, abnormal cytokine expression, bone marrow fibrosis, anemia, splenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

DIAGNOSIS is based on bone marrow morphology. The presence of JAK2, CALR, or MPL mutation is supportive but not essential for diagnosis; approximately 90% of patients carry one of these mutations and 10% are "triple-negative." None of these mutations are specific to PMF and are also seen in essential thrombocythemia (ET). Prefibrotic PMF mimics ET in its presentation and the distinction, enabled by careful bone marrow morphological examination, is prognostically relevant. Differential diagnosis also includes chronic myeloid leukemia, myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia.

RISK STRATIFICATION

The Dynamic International Prognostic Scoring System-plus (DIPSS-plus) uses eight predictors of inferior survival: age >65 years, hemoglobin <10 g/dL, leukocytes >25 × 10(9) /L, circulating blasts ≥1%, constitutional symptoms, red cell transfusion dependency, platelet count <100 × 10(9) /L, and unfavorable karyotype (i.e., complex karyotype or sole or two abnormalities that include +8, -7/7q-, i(17q), inv(3), -5/5q-, 12p-, or 11q23 rearrangement). The presence of 0, 1, "2 or 3," and ≥4 adverse factors defines low, intermediate-1, intermediate-2, and high-risk disease with median survivals of approximately 15.4, 6.5, 2.9, and 1.3 years, respectively. High risk disease is also defined by CALR(-) /ASXL1(+) mutational status.

RISK-ADAPTED THERAPY

Observation alone is adequate for asymptomatic low/intermediate-1 risk disease, especially with CALR(+) /ASXL1(-) mutational status. Stem cell transplant is considered for DIPSS-plus high risk disease or any risk disease with CALR(-) /ASXL1(+) mutational status. Investigational drug therapy is reasonable for symptomatic intermediate-1 or intermediate-2 risk disease. Splenectomy is considered for drug-refractory splenomegaly. Involved field radiotherapy is most useful for post-splenectomy hepatomegaly, non-hepatosplenic EMH, PMF-associated pulmonary hypertension, and extremity bone pain.

[Spinal cord compression due to extramedullary hematopoiesis in a patient with myelofibrosis]

Development and growth of hematopoietic tissue outside of the bone marrow is termed extramedullary hematopoiesis (EMH). It occurs in patients with hematological diseases such as myelofibrosis and thalassemia. Liver and spleen are the usual sites of EMH. However, spinal cord compression caused by EMH is a rare complication. A 65-year-old man with myelofibrosis was admitted to our hospital with progressive paraparesis. Thoracic spine MRI revealed epidural masses causing cord compression. Histological examination of the epidural mass showed evidence of EMH consisting of megakaryocytic and erythroid hyperplasia. After surgical decompression and radiotherapy, lower limb weakness and sensory disturbance were significantly improved. MRI showed disappearance of the spinal cord compression. With this therapy, he had no recurrence until he died of myelofibrosis. Spinal EMH should be considered as a differential diagnosis in patients with hematological diseases presenting with paraparesis. Surgical decompression and radiotherapy are effective approaches for the treatment of paraparesis due to EMH.

The renal sinus--transitional cell carcinoma and its mimickers on computed tomography

The renal sinus is a deep recess located at the medial aspect of the kidney surrounded by the renal parenchyma. It contains within it the collecting system of the kidney, lymphatics, nerves, and renal blood vessels. The remainder of the sinus is filled with adipose and fibrous tissue. A variety of pathological conditions arise from the different tissues in this site. The aim of this review is to explore and illustrate the common and less common processes affecting the renal pelvis.

Extramedullary hematopoiesis in uterine leiomyoma associated with numerous intravascular thrombi

We report a case of extramedullary hematopoiesis (EMH) in uterine leiomyoma and associated numerous intravascular thrombi. A 29-year-old nulliparous female presented with heavy vaginal bleeding and a hematocrit of 22%. No bone marrow biopsy has been performed. She had a history of uterine leiomyomata and menorrhagia for a year. A transvaginal ultrasound confirmed the presence of a uterine leiomyoma. The patient was treated conservatively with oral contraceptive pills due to desire for fertility. However, she continued to have heavy vaginal bleeding and developed bilateral upper extremity deep vein thrombosis and multiple superficial vein thromboses after two months. An exploratory laparotomy with uterine myomectomy was performed. Gross examination of the specimen revealed a single nodular mass measuring 10.0 × 9.5 × 7.5 cm with a white-tan swirling cut surface. Microscopic examination revealed benign smooth muscle consistent with leiomyoma and numerous intravascular thrombi both with areas of EMH. Immunohistochemical stains confirmed the presence of all three benign lineages of hematopoietic cells. Occurrence of EMH in uterine leiomyoma and intravascular thrombi is very rare. It may be related to systemic hematopoietic stimulation due to severe chronic anemia and local presence of hematopoietic growth factors and/or cytokines.

Myelofibrosis-associated complications: pathogenesis, clinical manifestations, and effects on outcomes

Myelofibrosis (MF) is a rare chronic BCR-ABL1 (breakpoint cluster region-Abelson murine leukemia viral oncogene homologue 1)-negative myeloproliferative neoplasm characterized by progressive bone marrow fibrosis, inefficient hematopoiesis, and shortened survival. The clinical manifestations of MF include splenomegaly, consequent to extramedullary hematopoiesis, cytopenias, and an array of potentially debilitating abdominal and constitutional symptoms. Dysregulated Janus kinase (JAK)-signal transducer and activator of transcription signaling underlies secondary disease-associated effects in MF, such as myeloproliferation, bone marrow fibrosis, constitutional symptoms, and cachexia. Common fatal complications of MF include transformation to acute leukemia, thrombohemorrhagic events, organ failure, and infections. Potential complications from hepatosplenomegaly include portal hypertension and variceal bleeding, whereas extramedullary hematopoiesis outside the spleen and liver - depending on the affected organ - may result in intracranial hypertension, spinal cord compression, pulmonary hypertension, pleural effusions, lymphadenopathy, skin lesions, and/or exacerbation of abdominal symptoms. Although allogeneic stem cell transplantation is the only potentially curative therapy, it is suitable for few patients. The JAK1/JAK2 inhibitor ruxolitinib is effective in improving splenomegaly, MF-related symptoms, and quality-of-life measures. Emerging evidence that ruxolitinib may be associated with a survival benefit in intermediate- or high-risk MF suggests the possibility of a disease-modifying effect. Consequently, ruxolitinib could provide a treatment backbone to which other (conventional and novel) therapies may be added for the prevention and effective management of specific MF-associated complications.

Myelofibrosis-associated complications: pathogenesis, clinical manifestations, and effects on outcomes

Myelofibrosis (MF) is a rare chronic BCR-ABL1 (breakpoint cluster region-Abelson murine leukemia viral oncogene homologue 1)-negative myeloproliferative neoplasm characterized by progressive bone marrow fibrosis, inefficient hematopoiesis, and shortened survival. The clinical manifestations of MF include splenomegaly, consequent to extramedullary hematopoiesis, cytopenias, and an array of potentially debilitating abdominal and constitutional symptoms. Dysregulated Janus kinase (JAK)-signal transducer and activator of transcription signaling underlies secondary disease-associated effects in MF, such as myeloproliferation, bone marrow fibrosis, constitutional symptoms, and cachexia. Common fatal complications of MF include transformation to acute leukemia, thrombohemorrhagic events, organ failure, and infections. Potential complications from hepatosplenomegaly include portal hypertension and variceal bleeding, whereas extramedullary hematopoiesis outside the spleen and liver - depending on the affected organ - may result in intracranial hypertension, spinal cord compression, pulmonary hypertension, pleural effusions, lymphadenopathy, skin lesions, and/or exacerbation of abdominal symptoms. Although allogeneic stem cell transplantation is the only potentially curative therapy, it is suitable for few patients. The JAK1/JAK2 inhibitor ruxolitinib is effective in improving splenomegaly, MF-related symptoms, and quality-of-life measures. Emerging evidence that ruxolitinib may be associated with a survival benefit in intermediate- or high-risk MF suggests the possibility of a disease-modifying effect. Consequently, ruxolitinib could provide a treatment backbone to which other (conventional and novel) therapies may be added for the prevention and effective management of specific MF-associated complications.

Extramedullary hematopoiesis within cystic renal cell carcinoma with oncocytic and chromophobe cell types: A case report

Extramedullary hematopoiesis (EMH) is a phenomenon in which hematopoietic cells are found in sites other than the bone marrow. It is usually observed in the liver and spleen but may occasionally be found within solid tumors. The current case report presents a 69-year-old female patient who presented with a renal cyst. Histopathological examination following surgical removal of the cyst revealed a lining of oncocytic- and chromophobe-type cells with capsular invasion and a mass forming EMH with evident bone trabeculae within the cyst wall. Circulating hematopoietic stem cells in the blood and their colonization within tissues is discussed in the present case report, emphasizing certain types of renal cell carcinoma.

Pulmonary hypertension associated with chronic hemolytic anemia and other blood disorders

Pulmonary hypertension (PH) has emerged as a major complication of several hematologic disorders, including hemoglobinopathies, red cell membrane disorders, chronic myeloproliferative disorders, and splenectomy. With the exception of sickle cell disease, there are a limited number of studies systematically evaluating the prevalence of PH using the gold standard right heart catheterization in these disorders. The cause of the PH in patients with hematologic disorders is multifactorial, and a thorough diagnostic evaluation is essential. More importantly, there are virtually no high-quality data on the safety and efficacy of PH-targeted therapy in this patient population.

Presacral extramedullary hematopoiesis: an alternative hypothesis

Idiopathic extramedullary hematopoiesis (EMH) is the production of blood cells outside of the bone marrow without an underlying hematological pathology. This article examines the rare case of idiopathic EMH in the presacral area. A 65-year-old woman with a past medical history of a total abdominal hysterectomy and a negative hematological history presented with back and leg pain. MRI revealed a presacral mass. Fine needle aspiration revealed a diagnosis of EMH. The patient was managed conservatively with serial imaging. We present this patient with rare idiopathic, presacral EMH and review the literature on this topic. The current pathophysiology suggests that sacral fractures release hematopoietic stem cells, which in turn replicate to form an EMH mass. This review suggests a second mechanism in which surgical manipulation of the uterine tissue releases mesenchymal stem cells. These cells differentiate into stromal tissue that interacts with multipotent hematopoietic stem cells in order to form an EMH mass. Thus, idiopathic, presacral EMH may develop from either bone fractures or surgical manipulation of the uterus. Management of these patients should include watchful waiting unless intractable pain, new-onset weakness, or bowel/bladder dysfunction develops.

Extramedullary hematopoiesis in the uterine cervix associated with tissue repair

Extramedullary hematopoiesis (EMH) is the presence of hematopoietic precursors outside the bone marrow. This condition is usually associated with hematologic disorders. Although EMH can be found in almost every site in the body, female genital tract involvement is rare. The authors report EMH in the uterine cervix from a 64-year-old patient following cervical biopsy due to abnormal cervical cytology. Neither neoplasm nor hematologic disorder was detected before the diagnosis and after 1 year of follow up. To the best of our knowledge, this is the first reported case of EMH involving the uterine cervix which showed an association with tissue repair.

Agnogenic myeloid metaplasia with pulmonary hematopoiesis

Agnogenic myeloid metaplasia (AMM) is characterized by bone marrow fibrosis, splenomegaly and leukoerythroblastic anemia and is frequently accompanied by extramedullary hematopoiesis (EMH). Pulmonary interstitial EMH associated with myelofibrosis has rarely been described in the medical literature and is usually fatal. We report the case of a 77-year-old man with agnogenic myeloid metaplasia (AMM) treated with hydroxyurea, who seven years after diagnosis presented with dyspnea and severe hypoxemia. Radionuclide bone marrow scanning demonstrated increased tracer activity on the bases of both lungs, consistent with non-hepatosplenic EMH. Pulmonary EMH is rare in patients with AMM, but should be considered in patients with hypoxemia and respiratory distress.

Peritoneal EMH in a Dog with Immune-Mediated Hemolytic Anemia

Extramedullary hematopoiesis (EMH) is the process by which normal blood cells are produced outside the bone marrow. In humans, EMH effusions are rare and are characterized by the presence of megakaryocytes, immature erythrocytes, immature leukocytes, or combinations of those cells. To the authors’ knowledge, this is the first report to describe a case of peritoneal EMH effusion in a dog. A 5 yr old castrated male shorthaired dachshund presented with a 2 day history of pigmenturia and inappetence. A complete blood count revealed regenerative anemia with marked agglutination, spherocytosis, and an acute inflammatory leukogram characterized by a neutrophilia, regenerative left shift, and monocytosis. Ultrasound-guided aspiration of peritoneal effusion yielded a sample of high nucleated cellularity predominantly composed of mature and immature neutrophils and erythroid precursor cells. The patient was diagnosed with primary immune-mediated hemolytic anemia with concurrent EMH peritoneal effusion. The following case description and discussion explore the clinical findings associated with the unusual effusion and outline the possible pathogenesis by which the EMH effusion may have arisen in the dog.

A surprising cause of masses in the chest

An 82-year-old male presented to the emergency department with an acute onset of chest pain and mild shortness of breath at rest. The pain in his left lower chest was pleuritic with intensity 9- on a 10-point scale. He had driven 2 h in his car that day, but had no other prolonged immobility. About 15 years previously, he was found to have increased hemoglobin (18.1 g/dL) and diagnosed with secondary erythrocytosis due to active smoking, chronic obstructive pulmonary disease (COPD), and residence in Payson, Arizona (altitude 4,999 ft). Polycythemia vera was entertained, but not pursued due to multiple secondary risks. He had been treated with daily aspirin and monthly phlebotomies to maintain a hematocrit below 45%. He also had a history of superficial thrombophlebitis, nephrolithiasis, hypertension and superficial transitional cell carcinoma of the bladder resected and in remission. There was also a deep venous thrombosis (DVT) and pulmonary embolism (PE) 13 years previously, believed to be provoked by prolonged immobility after a radical prostatectomy for prostate cancer now in remission. His medications were aspirin and lisinopril; he had no known drug allergies. He quit smoking 2 years prior after a 70 pack-year history. There was no other family history of thrombosis or bleeding disorder, autoimmune disorders, pulmonary disease or malignancy.

Intracranial extramedullary hematopoiesis: a rare cause of headaches

BACKGROUND

Ectopic bone marrow production, known as extramedullary hematopoiesis, may result in symptoms due to compression on normal structures. We present the multimodality imaging findings and subsequent management of a rare case of symptomatic extramedullary hematopoiesis within the calvarium.

METHODS

Case report.

RESULTS

A 54-year-old male with a history of myelofibrosis and no previous diagnosis of a headache disorder presented to the emergency department with worsening severe bilateral headaches. A nonenhanced CT of the brain was performed and diffuse extra-axial nodular hyperdensities were visualized. MRI of the brain demonstrated diffuse extra-axial avidly enhancing nodular masses, dural thickening and marked susceptibility. No paravertebral masses, typical for extramedullary hematopoiesis, were present in the chest or abdomen. Although the clinical team considered a biopsy to confirm the diagnosis, we suggested a noninvasive confirmatory test. The subsequent Tc99m sulfur colloid scan corroborated the diagnosis. The patient was then referred to radiation oncology for treatment.

CONCLUSION

In summary, extramedullary hematopoiesis is a hematologic compensatory disorder that rarely occurs within the CNS and may cause neurological compromise due to compression on underlying structures. The diagnosis can be made with noninvasive imaging and treated with low dose radiation therapy.

Acute toxicity of amorphous silica nanoparticles in intravenously exposed ICR mice

This study aimed to evaluate the acute toxicity of intravenously administrated amorphous silica nanoparticles (SNPs) in mice. The lethal dose, 50 (LD₅₀), of intravenously administrated SNPs was calculated in mice using Dixon's up-and-down method (262.45±33.78 mg/kg). The acute toxicity was evaluated at 14 d after intravenous injection of SNPs at 29.5, 103.5 and 177.5 mg/kg in mice. A silicon content analysis using ICP-OES found that SNPs mainly distributed in the resident macrophages of the liver (10.24%ID/g), spleen (34.78%ID/g) and lung (1.96%ID/g). TEM imaging showed only a small amount in the hepatocytes of the liver and in the capillary endothelial cells of the lung and kidney. The levels of serum LDH, AST and ALT were all elevated in the SNP treated groups. A histological examination showed lymphocytic infiltration, granuloma formation, and hydropic degeneration in liver hepatocytes; megakaryocyte hyperplasia in the spleen; and pneumonemia and pulmonary interstitial thickening in the lung of the SNP treated groups. A CD68 immunohistochemistry stain indicated SNPs induced macrophage proliferation in the liver and spleen. The results suggest injuries induced by the SNPs in the liver, spleen and lungs. Mononuclear phagocytic cells played an important role in the injury process.

Extramedullary hematopoiesis at the posterior mediastinum in patient with hereditary spherocytosis: a case report

Thoracic extramedullary hematopoiesis (EMH) is a rare disease entity that is usually associated with hematologic disorders, such as myelodysplastic or hemolytic disease. Because thoracic EMH is usually encountered as a mass during radiologic examinations, it should be differentiated from posterior mediastinal neurogenic tumors. Here, the authors report a case of EMH associated with hereditary spherocytosis. The patient underwent a complete excision by thoracoscopic surgery to differentiate it from other mediastinal tumors.

Spinal cord compression secondary to extramedullary hematopoiesis in a dog

CASE DESCRIPTION

An 11-year-old spayed female Siberian Husky was evaluated because of a 2-week history of progressive paraparesis.

CLINICAL FINDINGS

Results of neurologic examination were consistent with a T3-L3 myelopathy. There were no abnormalities on CBC, and hypercalcemia was noted on serum biochemical analysis. Several hypoechoic splenic nodules were evident on abdominal ultrasonography, and results of fine-needle aspiration cytology were consistent with splenic extramedullary hematopoiesis (EMH). Two compressive, extradural masses in the dorsal epidural space of the thoracolumbar region of the spinal cord were seen on MRI images.

TREATMENT AND OUTCOME

A dorsal laminectomy was performed to remove the extradural spinal masses. Results of histologic examination of tissue samples were consistent with EMH. Following surgery, clinical signs of paraparesis resolved, and there was no recurrence of the masses 24 months after surgery.

CLINICAL RELEVANCE

Extramedullary hematopoesis should be considered as a differential diagnosis in dogs in which results of diagnostic imaging indicate a epidural mass. In human patients, spinal EMH usually occurs secondary to an underlying hematologic disease, but it can also occur spontaneously. Treatment options reported for humans include surgical decompression, radiation therapy, chemotherapy, and blood transfusion. The dog of this report responded favorably to surgical decompression and was clinically normal 2 years after surgery.

Contrast-enhanced ultrasound findings in a case of renal extramedullary hematopoiesis

We present the case of an 80-year-old man with two renal solid masses found at sonography, which were imaged by contrast-enhanced ultrasound, CT, and MRI and confirmed histologically. Contrast-enhanced ultrasound findings suggested a benign mass and a CT-guided biopsy yielded a diagnosis of extramedullary hematopoiesis.

Ectopic extramedullary hematopoiesis: evaluation and treatment of a rare and benign paraspinal/epidural tumor

Ectopic extramedullary hematopoiesis (EMH), defined as the formation of blood cells outside the bone marrow, usually occurs in a scenario of chronic anemia when, even after conversion of the bony yellow marrow to red marrow, the body is still unable to meet the demand for red blood cells. Ectopic extramedullary hematopoiesis most commonly occurs in the liver and spleen but may, in fact, occur almost anywhere in the body. Although previous reports have documented EMH presenting as paraspinal masses, such lesions have almost always been associated with a predisposing hematological disorder such as hemolytic anemia, myelofibrosis or myelodysplastic syndromes, thalassemia, polycythemia vera, leukemia, or lymphoma.

The authors of this report describe the first reported instance of EMH in a patient presenting with a symptomatic epidural and paraspinal cervical lesion arising from the posterior spinal elements and no known predisposing hematological disease. Initial radiographs revealed a bony lesion arising posteriorly from the C2–3 laminae and spinous processes. Subsequent imaging suggested the diagnosis, which was confirmed by CT-guided biopsy, peripheral blood smears, and bone marrow aspirate. Despite epidural compression and slight displacement of the cervical cord and thecal sac, the patient's symptoms were limited to pain and diminished cervical range of motion. Therefore, surgery was deferred in favor of nonsurgical therapy. Several alternative modalities for the treatment of EMH have been suggested in the literature, including cytotoxic agents and radiotherapy. The authors opted for an approach utilizing directed low-dose radiotherapy of a total of 25 Gy divided in 2.5-Gy fractions. At the 3-month follow-up, the patient continued to be asymptomatic, and MRI demonstrated a significant reduction in the dimensions of the lesion.

Extramedullary hematopoiesis with spinal cord compression in the absence of a preexisting hematological disorder has not been described in the context of clinical neurosurgical practice. Recognizing that EMH may present as an epidural or paraspinal lesion is important since chemotherapy and radiotherapy are effective therapeutic options in the majority of patients who suffer few if any symptoms. Extensive evaluation for underlying hematological disorders is necessary before undertaking directed therapy. Inadvertent resection of these highly vascularized masses may risk catastrophic intraoperative hemorrhage with no proven benefit as compared with medical treatment, which usually provides excellent long-term outcomes.

Bilateral pleural effusion in a patient with an extensive extramedullary hematopoietic mass

We present a 56-year-old woman with bilateral pleural effusions, widespread enlarged lymph nodes, and soft tissue masses located within the renal pelvis. The initially working diagnosis was tuberculosis and lymphoma. Further pathological examination of the lymph node biopsy confirmed a diagnosis of extramedullary hematopoiesis, and a bone marrow biopsy revealed myelofibrosis. Unlike common treatment options such as radiotherapy and/or surgery, intrathoracic cisplatin and dexamethasone for the treatment of pleural effusions secondary to extramedullary hematopoiesis demonstrated an improvement in feasibility and efficacy in the present case.

Implantable microenvironments to attract hematopoietic stem/cancer cells

The environments that harbor hematopoietic stem and progenitor cells are critical to explore for a better understanding of hematopoiesis during health and disease. These compartments often are inaccessible for controlled and rapid experimentation, thus limiting studies to the evaluation of conventional cell culture and transgenic animal models. Here we describe the manufacture and image-guided monitoring of an engineered microenvironment with user-defined properties that recruits hematopoietic progenitors into the implant. Using intravital imaging and fluorescence molecular tomography, we show in real time that the cell homing and retention process is efficient and durable for short- and long-term engraftment studies. Our results indicate that bone marrow stromal cells, precoated on the implant, accelerate the formation of new sinusoidal blood vessels with vascular integrity at the microcapillary level that enhances the recruitment hematopoietic progenitor cells to the site. This implantable construct can serve as a tool enabling the study of hematopoiesis.

Extramedullary hematopoiesis involving uterus, fallopian tubes, and ovaries, mimicking bilateral tuboovarian abscesses

Extramedullary hematopoiesis (EMH) is normal during fetal life, but after birth, the presence of EMH is considered to be abnormal. The most common sites for EMH are the liver, the spleen, and paraspinal regions of the thorax; however, it has been reported to involve virtually any organ or tissue. To our knowledge, this is the first reported case of EMH involving the entire upper genital tract, including the uterus, fallopian tubes, and ovaries. A 43-yr-old African American woman presented with a tender pelvic mass and a markedly elevated white blood cell count. Imaging was consistent with bilateral tuboovarian abscesses. Laparotomy and removal of uterus, tubes, and ovaries and bone marrow biopsy confirmed chronic myelogenous leukemia in the chronic phase and EMH in the cervix, endometrium, and ovaries, and no evidence of infection. We believe this to be the first reported case of EMH involving all organs of the upper genital tract presenting in a patient who has chronic myelogenous leukemia but not in blast crisis. This case illustrates the importance of a broad differential diagnosis when managing a patient with a pelvic mass and the value of a multidisciplinary team approach.

Donor lymphocyte infusions and second transplantation as salvage treatment for relapsed myelofibrosis after reduced-intensity allografting

Thirty myelofibrosis patients (21 males, nine females) with relapse (n = 27) or graft-rejection (n = 3) after dose-reduced allografting underwent a salvage strategy including donor lymphocyte infusions (DLIs) and/or second allogeneic haematopoietic stem cell transplantation (HSCT). Twenty-six patients received a median number of three (range, 1-5) DLIs in a dose-escalated mode starting with a median dose of 1·2 × 10(6) (range, 0·003-8 × 10(6) ) up to median dose of 40 × 10(6) T-cells/kg (range, 10-130 × 10(6) ). 10/26 patients (39%) achieved complete response (CR) to DLIs. Acute (grade II-IV) and chronic graft-versus-host (GvHD) disease occurred in 12% and 36% cases. Thirteen non-responders to DLI and four patients who did not receive DLI due to graft-rejection or acute transformation of the blast phase underwent a second allogeneic HSCT from alternative (n = 15) or the same (n = 2) donor. One patient (6%) experienced primary graft-failure and died. Acute (II-IV) and chronic GvHD were observed in 47% and 46% of patients. Overall responses after second HSCT were seen in 12/15 patients (80%: CR: n = 9, partial response: n = 3). The 1-year cumulative incidence of non-relapse mortality for recipients of a second allograft was 6%, and the cumulative incidence of relapse was 24%. After a median follow-up of 27 months, the 2-year overall survival and progression-free survival for all 30 patients was 70% and 67%, respectively. In conclusion, our two-step strategy, including DLI and second HSCT for non-responding or ineligible patients, is an effective and well-tolerated salvage approach for patients relapsing after reduced-intensity allograft after myelofibrosis.

Mass-like extramedullary hematopoiesis: imaging features

PURPOSE

To report the imaging appearances of mass-like extramedullary hematopoiesis (EMH), to identify those features that are sufficiently characteristic to allow a confident diagnosis, and to recognize the clinical conditions associated with EMH and the relative incidence of mass-like disease.

MATERIALS AND METHODS

We retrospectively identified 44 patients with EMH; 12 of which (27%) had focal mass-like lesions and formed the study group. The study group consisted of 6 male and 6 female subjects with a mean age of 58 years (range 13-80 years). All 12 patients underwent CT imaging and 3 of the 12 patients had undergone additional MR imaging. The imaging characteristics of the extramedullary hematopoiesis lesions in the study group were analyzed and recorded. The patient's clinical presentation, including any condition associated with extramedullary hematopoiesis, was also recorded.

RESULTS

Ten of the 12 (83%) patients had one or more masses located along the axial skeleton. Of the 10 patients with axial masses, 9 (90%) had multiple masses and 7 (70%) demonstrated internal fat. Eight patients (80%) had paraspinal masses and 4 patients (40%) had presacral masses. Seven patients (70%) had splenomegaly. Eleven of the 12 patients had a clinical history available for review. A predisposing condition for extramedullary hematopoiesis was present in 10 patients and included various anemias (5 cases; 45%), myelofibrosis/myelodysplastic syndrome (4 cases; 36%), and marrow proliferative disorder (1 case; 9%). One patient had no known predisposing condition.

CONCLUSION

Mass-like extramedullary hematopoiesis most commonly presents as multiple, fat-containing lesions localized to the axial skeleton. When these imaging features are identified, extramedullary hematopoiesis should be strongly considered, particularly when occurring in the setting of a predisposing medical condition.

Post-traumatic pelvic extramedullary haemopoetic tissue causing lower urinary tract symptoms

Extramedullary haemopoiesis (EMH) is the abnormal development and growth of haemopoietic tissue outside the bone marrow. It is usually asymptomatic and occurs in the presence of myelodysplastic syndromes. In this report, we describe the first post-traumatic EMH presenting with lower urinary tract symptoms.

Myelodysplasia presenting as thoracic spinal epidural extramedullary hematopoiesis: a rare treatable cause of spinal cord myelopathy

We present clinical, magnetic resonance imaging, and pathological findings of a 61-year-old patient with an otherwise asymptomatic myelodysplastic syndrome presenting with progressive paraparesis from epidural thoracic spinal extramedullary hematopoiesis. Surgical spinal cord decompression resulted in complete clinical remission.

Extramedullary hematopoiesis: a new look at the underlying stem cell niche, theories of development, and occurrence in animals

Extramedullary hematopoiesis (EMH) is the formation and development of blood cells outside the medullary spaces of the bone marrow. Although widely considered an epiphenomenon, secondary to underlying primary disease and lacking serious clinical or diagnostic implications, the presence of EMH is far from incidental on a molecular basis; rather, it reflects a well-choreographed suite of changes involving stem cells and their microenvironment (the stem cell niche). The goals of this review are to reconsider the molecular basis of EMH based on current knowledge of stem cell niches and to examine its role in the pathophysiologic mechanisms of EMH in animals. The ability of blood cells to home, proliferate, and mature in extramedullary tissues of adult animals reflects embryonic patterns of hematopoiesis and establishment or reactivation of a stem cell niche. This involves pathophysiologic alterations in hematopoietic stem cells, extracellular matrix, stromal cells, and local and systemic chemokines. Four major theories involving changes in stem cells and/or their microenvironment can explain the development of most occurrences of EMH: (1) severe bone marrow failure; (2) myelostimulation; (3) tissue inflammation, injury, and repair; and (4) abnormal chemokine production. EMH has also been reported within many types of neoplasms. Understanding the concepts and factors involved in stem cell niches enhances our understanding of the occurrence of EMH in animals and its relationship to underlying disease. In turn, a better understanding of the prevalence and distribution of EMH in animals and its molecular basis could further inform our understanding of the hematopoietic stem cell niche.

Morphological study of synovial changes in two-stage reconstructions of the infected hip and knee arthroplasties

OBJECTIVES

To study the morphological changes of the regenerating synovium in two-stage revision arthroplasty, which is the gold standard for treatment of periprosthetic joint infection.

DESIGN

The authors analysed a series of synovial biopsies to examine morphological changes in healing periprosthetic tissues damaged by previous surgery and infection.

METHODS

Synovial tissues from 19 patients (10 knees and 9 hips) who underwent a two-stage exchange surgery for periprosthetic infection were reviewed and correlated with clinical and laboratory findings.

SETTING

Retrospective morphological study.

PARTICIPANTS

Archival tissues from 19 two-stage revision arthroplasties in adult patients.

RESULTS

Healing synovial tissue obtained at the reimplantation surgery showed characteristic layering: superficial fibrin exudate, immature richly vascularised granulation tissue and deeper maturing granulation tissue and fibrosis. Although increased neutrophil counts were found in the majority of cases, 2 of 19 cases showed dense infiltrates indicative of persistent infection, which correlated with positive microbiology in one case. One of the cases failed due to acetabular loosening and two cases failed due to late superinfection. One case showed a dense infiltration of eosinophils suggestive of a hypersensitivity reaction, which was subsequently proven by cutaneous tests. Foci of extramedullary haematopoiesis were detected in two cases.

CONCLUSIONS

We observed characteristic morphological changes in the healing synovial tissue during reimplantation surgery for periprosthetic infection in serologically and microbiologically sterile tissues. Substantial increased counts of synovial neutrophils (>200 cells/10 high-power fields) seem to be indicative of persistent infection of the joint; therefore, prolonged antibiotic therapy should be considered in positive cases.

Extramedullary hematopoiesis in leiomyoma uteri

Extramedullary hematopoiesis (EMH) that often occurs as a compensatory reaction to an underlying hematologic abnormality is a non-neoplastic proliferation of hematopoietic tissue outside the bone marrow and peripheral blood. Rarely, EMH may be seen in hematologically normal individuals. EMH is most commonly (95%) seen in reticuloendothelial organs such as the spleen, liver, and lymph nodes but has rarely been reported in other locations. EMH is extremely rare in the uterus. In this case report, we present EMH in leiomyoma uteri in patients without any underlying hematologic abnormalities. Very rare clinical conditions like EMH can be observed in cases of myoma uteri and therefore should be kept in mind. There is currently no consensus regarding the pathogenesis and clinical management of this uncommon pathology and further reports on this topic are needed.

Pulmonary extramedullary haematopoiesis

A 72-year-old Caucasian lady with myeloproliferative disorder was admitted for evaluation of progressive dyspnoea, weight loss, fatigue and mild hypoxia. A diffuse ground glass opacity was seen on CT pulmonary angiogram. Differential diagnoses included heart failure, infection, progression of myeloproliferative disorder with extramedullary haematopoiesis, thromboembolism or hydroxyurea-induced lung injury. Bronchoscopy and broncho-alveolar lavage were uninformative however lung biopsy with video-assisted thoracoscopy revealed extramedullary haematopoiesis within lung parenchyma. This is a very rare complication of myeloproliferative disorder and the authors discuss the significance of the case, review the literature and report the patient's progress.

Extramedullary hematopoiesis in unusual locations in hematologically compromised and noncompromised patients

Extramedullary hematopoiesis (EMH) occurs as a compensatory reaction to an underlying hematologic abnormality. EMH is most commonly seen in the liver and spleen but rarely has been reported in other locations, as well. On rare occasions, EMH may mimic a neoplasm in hematologically noncompromised patients. In this report, we present three cases of EMH in unusual locations, two in the presacral soft tissue and one in the synovial lining of the knee joint. The patients with presacral masses had no hematologic abnormality. In all patients with EMH, imaging plays an important role in both localization of the lesion and guidance for the biopsy; when imaging results are correlated with histological findings, the diagnosis of EMH can be confirmed.

Case of polycythemia vera with unusual organizing pneumonia mimicking the clinical features of military tuberculosis and possibly caused by the involvement of neoplastic megakaryocytes

Polycythemia vera (PV) is a clonal myeloproliferative neoplasm (MPN) of hematopoietic stem cells. Although the management of MPN patients generally focuses on the prevention of thromboembolic events caused by hypercoagulability, it is true that the patients with hematological malignancy often suffer from pulmonary diseases with atypical radiological patterns. We present here a 56-year-old woman with PV harboring a JAK2(V617F) mutation that had a diffuse reticulonodular pattern on chest radiography and was initially suspected of having military tuberculosis. Pathological assessment of a video-assisted thoracoscopic surgery lung biopsy revealed that the lesions were in fact organizing pneumonia (OP). Interestingly, pulmonary extramedullary hematopoiesis with a diffuse plugging of the alveolar blood capillaries by numerous atypical megakaryocytes was also observed around the granulation components. The histological findings of our case of unusual OP suggest that local activated neoplastic megakaryocytes and platelets played an important role in the development of spreading fibrotic lesions. JAK2 mutation or the preleukemic phase of MPN may accelerate the activation of megakaryocytes and result in the proliferative process of fibrosis.

How I treat myelofibrosis

It is currently assumed that myelofibrosis (MF) originates from acquired mutations that target the hematopoietic stem cell and induce dysregulation of kinase signaling, clonal myeloproliferation, and abnormal cytokine expression. These pathogenetic processes are interdependent and also individually contributory to disease phenotype-bone marrow stromal changes, extramedullary hematopoiesis, ineffective erythropoiesis, and constitutional symptoms. Molecular pathogenesis of MF is poorly understood despite a growing list of resident somatic mutations that are either functionally linked to Janus kinase (JAK)-signal transducer and activator of transcription hyperactivation (eg JAK2, MPL, and LNK mutations) or possibly involved in epigenetic dysregulation of transcription (TET2, ASXL1, or EZH2 mutations). Current prognostication in primary MF is based on the Dynamic International Prognostic Scoring System-plus model, which uses 8 independent predictors of inferior survival to classify patients into low, intermediate 1, intermediate 2, and high-risk disease groups; corresponding median survivals are estimated at 15.4, 6.5, 2.9, and 1.3 years. Such information is used to plan a risk-adapted treatment strategy for the individual patient, which might include observation alone, conventional or investigational (eg, JAK inhibitors, pomalidomide) drug therapy, allogenic stem cell transplantation with reduced- or conventional-intensity conditioning, splenectomy, or radiotherapy. I discuss these treatment approaches in the context of who should get what and when.

Extramedullary hematopoiesis: an unusual finding in subdural hematomas

We present a case of a 59-year-old man who was found to have clusters of hyperchromatic, small, round nucleated cells within a subdural hematoma removed after a skull fracture. Immunohistochemistry study confirmed that the cells were hematopoietic components predominantly composed of normoblasts. In this paper, we describe the clinical and pathological findings. A brief review of published information on extramedullary hematopoiesis in subdural hematoma and the mechanisms of pathogenesis are also discussed. While extramedullary hematopoiesis is seen anecdotally by neuropathologists in chronic subdural hematomas, only a few cases are documented in the literature. Furthermore, extramedullary hematopoiesis in subdural hematoma can pose a diagnostic challenge for general pathologists who encounter subdural hematoma evacuations seldom in their surgical pathology practices.

Uterine extramedullary hematopoiesis: what is the clinical significance?

Extramedullary hematopoiesis (EMH) represents abnormal development and growth of hematopoietic tissue outside the bone marrow. Recent studies have shown its association with myelofibrosis and myeloid metaplasia, chronic myeloproliferative disorders, and other hematologic malignancies in up to two-thirds of the cases. Eleven cases of uterine EMH (UEMH) have been reported earlier; of these half had a concurrent, or subsequently developed a clinically significant hematologic disorder. We studied a larger group of patients with UEMH to understand the relationship with hematologic disorders. Cases diagnosed as UEMH between 1995 and 2007 were retrieved from our files (n=20). UEMH was confirmed in all 20 cases. Eighteen cases were located in the fundus including 5 in endometrial polyps and 5 in leiomyomas. Two foci were located within the cervix. The erythroid lineage was present in all foci; 35% also had myeloid precursors, and 2% had megakaryocytes. Twelve of 20 patients had underlying anemia (mean Hgb of 11 mg/dL, range: 5.5 to 15.7 mg/dL). No preexisting hematologic malignancy was identified in any of the patients. Follow-up information was available on 17 patients (mean: 2.88 yr; range: 0.2 to 9 yr). None of the patients developed a significant hematologic disorder other than anemia during follow-up. On the basis of our study, UEMH is frequently associated with chronic anemia. In comparison with existing literature suggesting a strong link between UEMH and hematopoietic disorders, our findings suggest that UEMH is rarely associated with serious underlying hematologic conditions and therefore does not warrant extensive hematologic workup.