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

Extramedullary hematopoiesis in cancer

Hematopoiesis can occur outside of the bone marrow during inflammatory stress to increase the production of primarily myeloid cells at extramedullary sites; this process is known as extramedullary hematopoiesis (EMH). As observed in a broad range of hematologic and nonhematologic diseases, EMH is now recognized for its important contributions to solid tumor pathology and prognosis. To initiate EMH, hematopoietic stem cells (HSCs) are mobilized from the bone marrow into the circulation and to extramedullary sites such as the spleen and liver. At these sites, HSCs primarily produce a pathological subset of myeloid cells that contributes to tumor pathology. The EMH HSC niche, which is distinct from the bone marrow HSC niche, is beginning to be characterized. The important cytokines that likely contribute to initiating and maintaining the EMH niche are KIT ligands, CXCL12, G-CSF, IL-1 family members, LIF, TNFα, and CXCR2. Further study of the role of EMH may offer valuable insights into emergency hematopoiesis and therapeutic approaches against cancer. Exciting future directions for the study of EMH include identifying common and distinct EMH mechanisms in cancer, infectious diseases, and chronic autoimmune diseases to control these conditions.

Congenital asplenia impairs heme-iron recycling during erythropoiesis in zebrafish

The spleen is postulated to be a hematopoietic tissue in adult fish; however, clear evidence is still lacking to define its role in hematopoietic activity. In our previous study, a congenitally asplenic zebrafish was generated though gene editing, which provided a new perspective for studying the role of fish spleen in hematopoiesis. In this study, HSC-regulated and erythrocyte marker genes, such as gata1a, gata2, klf1, hbaa1, hbaa2, hbba1 and hbba2 were significantly reduced in congenitally asplenic zebrafish when compared with wild-type (WT). Subsequently, we conducted the transcriptome profiles of whole kidneys from WT and congenitally asplenic zebrafish to explore the possible molecular mechanisms underlying the impaired erythropoiesis caused by congenital asplenia. Our results demonstrated that congenital asplenia might impair heme-iron recycling during erythropoiesis, as evidenced by significant down-regulation of genes associated with iron acquisition (tfr1a, tfa, steap3 and slc25a37) and heme biosynthesis and transport (alas2, fech, uros, urod, copx, ppox and abcb10) in congenitally asplenic zebrafish. In addition, the down-regulation of hemopoiesis-related GO terms, including heme binding, tetrapyrrole binding, iron ion binding, heme metabolic process, heme biosynthetic process, erythrocyte differentiation, iron ion homeostasis and hemoglobin metabolic process confirmed the impaired erythropoiesis induced by congenital asplenia. Our study provides an in-depth understanding of spleen function in regulating heme-iron homeostasis during hematopoiesis, thereby providing valuable insights into pathological responses in splenectomized or congenitally asplenic patients.

Momelotinib expands the therapeutic armamentarium for myelofibrosis: Impact on hierarchy of treatment choices

The primary objective of treatment in myelofibrosis (MF) is prolongation of life, which is currently accomplished only by allogeneic hematopoietic stem cell transplantation (AHSCT). Determination of optimal timing for AHSCT is facilitated by molecular risk stratification. Non-transplant treatment options in MF are palliative in scope and include Janus kinase 2 (JAK2) inhibitors (JAKi): momelotinib (FDA approved on September 15, 2023), ruxolitinib (November 16, 2011), fedratinib (August 16, 2019), and pacritinib (February 28, 2022); all four JAKi are effective in reducing spleen size and alleviating symptoms, considered a drug class effect and attributed to their canonical JAK-STAT inhibitory mechanism of action. In addition, momelotinib exhibits erythropoietic effect, attributed to alleviation of ineffective erythropoiesis through inhibition of activin A receptor type-I (ACVR1). In transplant-ineligible or deferred patients, the order of treatment preference is based on specific symptoms and individual assessment of risk tolerance. Because of drug-induced immunosuppression and other toxicities attributed to JAKi, we prefer non-JAKi drugs as initial treatment for MF-associated anemia that is not accompanied by treatment-requiring splenomegaly or constitutional symptoms. Otherwise, it is reasonable to consider momelotinib as the first-line JAKi treatment of choice, in order to target the triad of quality-of-life offenders in MF: anemia, splenomegaly, and constitutional symptoms/cachexia. For second-line therapy, we favor ruxolitinib, over fedratinib, based on toxicity profile. Pacritinib and fedratinib provide alternative options in the presence of severe thrombocytopenia or ruxolitinib-resistance/intolerance, respectively. Splenectomy remains a viable option for drug-resistant symptomatic splenomegaly and cytopenia.

Hidden in the mediastinum: a case of extramedullary hematopoiesis unveiled through thoracoscopy

Extramedullary hematopoiesis (EMH) is a rare condition characterized by proliferation of hematopoietic stem cells outside the bone marrow, usually as a compensatory response to hematological disease. Although EMH primarily occurs in the liver and spleen, it can manifest in atypical locations, such as the mediastinum. We herein describe an asymptomatic 66-year-old man with incidentally discovered posterior mediastinal EMH. A 28- × 32-mm mass was detected during a routine examination. Laboratory findings were within normal limits. Computed tomography revealed a well-defined enhancing mass with a density of 60 Hounsfield units, suggestive of a neurogenic tumor. Surgical resection confirmed EMH, characterized by megakaryocytes and hematopoietic precursors. The patient recovered smoothly and was discharged 5 days postoperatively. Accurate preoperative diagnosis of EMH is challenging, as illustrated by this case. Although typically associated with anemia or hematological abnormalities, EMH can present without such signs. Surgical resection and histopathological examination are essential for diagnosis. This case emphasizes the diagnostic complexity of posterior mediastinal EMH, even in patients without overt hematological disorders. Posterior mediastinal EMH is exceedingly rare and diagnostically demanding. A high index of suspicion and histological tissue analysis are crucial for optimal management. Video-assisted thoracoscopic surgery enables both diagnosis and treatment through mass excision.

Extramedullary hematopoiesis in ribs and severe pulmonary hypertension disease following intermediate beta-thalassemia: a case report

BACKGROUND

Thalassemia is a type of congenital hemoglobinopathy that falls into the category of hemolytic anemias. Extramedullary hematopoiesis is a complication of this disease, which is a mechanism to compensate for chronic anemia in these patients, and imaging is the best diagnostic method.

CASE REPORT

In this report, a 36-year-old Caucasian female patient with intermediate beta thalassemia is presented who, at the time of referral, complained of exacerbated shortness of breath. Imaging showed diffuse expansion masses with soft tissue components in the ribs of both hemithoraxes, leading to the diagnosis of extramedullary hematopoiesis.

CONCLUSION

Extramedullary hematopoiesis in the ribs is an uncommon finding in patients with thalassemia and is a sign of the severity of the disease and a poor prognostic factor that might be preventable if blood transfusion begins at younger ages.

Paratesticular Extramedullary Hematopoiesis in Children

CONTEXT.—

Extramedullary hematopoiesis (EMH) is an uncommon occurrence, usually associated with hematologic disorders, but it rarely presents as an isolated finding.

OBJECTIVE.—

To determine the frequency, immunomorphologic features, and clinicopathologic background of EMH in orchiectomies from pediatric patients.

DESIGN.—

All orchiectomy specimens removed from children from 2008 to 2020 in our institution were retrospectively reviewed. Biopsies and neoplasias were excluded. The EMH diagnosis was rendered when hematopoietic cell precursors were present. Immunohistochemical stainings were performed to characterize the hematopoietic components.

RESULTS.—

Seventy-nine orchiectomies from 77 children (mean age, 5 years; range, 0-17 years) were included in our study. Forty-three patients (55.8%) underwent surgery for testicular atrophy, 30 (39.0%) for torsion, and 4 (5.2%) for intersex conditions. EMH was identified in 6 of 79 orchiectomies (7.6%), all performed for testicular torsion. All patients but one were newborns, and the remaining patient was 15 years old. No patient had evidence of a hematologic disorder. All EMH foci were in a background of reactive changes with a variable extension, either in the epididymis (4 cases) or in the deferens duct (2 cases). Immunostaining confirmed an association of myeloid (myeloperoxidase+) and erythroid precursors (E-cadherin+) in all 6 cases. One case also presented rare megakaryocytes, and one showed benign TdT+ B-cell precursors.

CONCLUSIONS.—

To our knowledge, this is the first study that demonstrates EMH as a common finding in orchiectomy samples, especially from newborns. Despite the lack of pathologic potential, it is important to recognize EMH in order to avoid misdiagnosis.

Cutaneous involvement in Ph-negative myeloproliferative neoplasms: from extramedullary hematopoiesis to myeloid metastasis with histiocytic differentiation. A systematic review of the literature

Myeloid neoplasms may metastasize to the skin, presenting a wide range of clinical-pathological features that often lead to a reduction in patients' survival. The presentation varies depending on the category of myeloid neoplasm and its prognostic significance. The literature has specifically focused on the features of acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and chronic myelomonocytic leukemia (CMML). In this article, we aimed to uncover the peculiarities of clonal skin proliferations in the course of Ph-negative myeloproliferative neoplasms (MPNs). We conducted a systematic review and statistical analysis of the literature data. MPN patients mainly exhibited cutaneous extramedullary hematopoiesis, while a minority displayed cutaneous histiocytic lesions. Furthermore, these patients showed lower survival rates compared to the median survival of MPN patients, especially when calculating survival from the appearance of cutaneous lesions. Our work highlights, for the first time, the prognostic relevance and histological heterogeneity of cutaneous lesions in MPN. Moreover, it emphasizes the importance of dermatological and histological examinations when cutaneous lesions are present.

Acute spinal cord compression in the setting of chronic extramedullary hematopoiesis of the thoracic spine

Background

Though rare, pathologic extramedullary hematopoiesis (EMH) can occur in response to myeloproliferative disorders and may present as paravertebral masses.

Case Description

We describe a 63-year-old female with unspecified thalassemia, hemochromatosis, and known asymptomatic extramedullary hematopoiesis of the thoracic spine who acutely developed severe spinal cord compression and a T9 vacuum phenomenon fracture 7 months after her initial diagnosis.

Outcome

The patient was treated with urgent decompression and T9 kyphoplasty, which resulted in complete resolution of her neurological deficits.

Conclusions

The timeline of symptomatology in the case suggests that asymptomatic patients with T-spine extramedullary hematopoiesis can develop progressive neurologic deterioration and atraumatic compression fractures culminating in acute spinal cord injury. While it may be appropriate to treat asymptomatic patients conservatively, surgical decompression must always remain a consideration.

Clinical Phenotype and Outcomes of Pulmonary Hypertension Associated with Myeloproliferative Neoplasms: A Population-based Study

Rationale: Precapillary pulmonary hypertension (PH) is a rare and largely unrecognized complication of myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (MF). Objectives: To describe characteristics and outcomes of MPN-associated PH. Methods: We report clinical, functional, and hemodynamic characteristics, classification, and outcomes of patients with PV, ET, or primary MF in the French PH registry. Measurements and Main Results: Ninety patients with MPN (42 PV, 35 ET, 13 primary MF) presented with precapillary PH with severe hemodynamic impairment, with a median mean pulmonary arterial pressure and pulmonary vascular resistance of 42 mm Hg and 6.7 Wood units, respectively, and impaired clinical conditions, with 71% in New York Heart Association functional classes III/IV and having a median 6-minute-walk distance of 310 m. Half of the patients were diagnosed with chronic thromboembolic PH (CTEPH); the other half were considered to have group 5 PH. MF was preferentially associated with group 5 PH, whereas PV and ET were generally related to CTEPH. Proximal lesions were diagnosed in half of the patients with CTEPH. Thromboendarterectomy was performed in 18 selected patients with high risk of complications (5 early deaths). Overall survival at 1, 3, and 5 years was 67%, 50%, and 34% in group 5 PH and 81%, 66%, and 42% in CTEPH, respectively. Conclusions: PH is a life-threatening condition potentially occurring in MPN. There are multiple mechanisms, with equal diagnoses of CTEPH and group 5 PH. Physicians should be aware that PH strongly affects the burden of patients with MPN, especially in group 5 PH, with unknown pathophysiological mechanisms.

Extramedullary hematopoietic pleural effusion in Waldenström's macroglobulinemia

Extramedullary hematopoietic effusion (EHE) is one of the extremely rare phenomena associated with extramedullary hematopoiesis, which is caused by serous effusions, including pleural effusion, and may be related to hematologic disorders and neoplasms. Herein, we present the case of an 81-year-old man with EHE accompanying Waldenström's macroglobulinemia (WM). The patient complained of anemia and dyspnea. The chest X-ray and computed tomography showed a massive left pleural effusion, and the aspirates revealed infiltration of the immature myeloid cells and megakaryocytes, in addition to the lymphoma cells. To our knowledge, this is the first report of EHE in WM.

Extramedullary Hematopoiesis Adjacent to Vertebral Fracture in a Patient with Pernicious Anemia: Support for a Mechanical Extrusion Mechanism

CASE

A 68-year-old woman presented with a paraspinal mass of indeterminate imaging characteristics. Workup and computed tomography-guided Fine Needle Aspiration (FNA) aspiration revealed extramedullary hematopoiesis (EMH) adjacent to a prior compression fracture in the setting of pernicious anemia.

CONCLUSION

The combination of findings suggests a possible relationship of the compression fracture and the EMH because of traumatic extravasation of marrow contents, with the patient's underlying anemia possibly providing an underlying predisposition to EMH.

Extramedullary hematopoiesis in gastric wall under early gastric cancer in a man with a myeloproliferative disorder: a case report

Extramedullary hematopoiesis (EMH) is the proliferation of hematopoietic stem cells outside the bone marrow and often observed in the liver, spleen in association with myeloproliferative disorders. On the other hand, EMH in the gastric wall is extremely rare. We report a rare case of EMH foci coexisting with early gastric cancer, which resulted in severe gastrointestinal bleeding. A 70-year-old male was diagnosed with myelofibrosis 4 years ago and visited our emergency room with a complaint of hematemesis and tarry stools. Upper gastrointestinal endoscopy revealed three early-stage gastric cancers in the lower gastric body and antrum, and biopsy was performed. Persistent bleeding at the biopsy site of the hypogastric lesion led to the consideration of surgical intervention. An open distal gastrectomy was performed. Postoperative histopathological examination revealed the tumor of the lower gastric body had EMH foci associated with myelofibrosis.

Coexisting Extra-Medullary Manifestation of Chronic Myelomonocytic Leukemia and Follicular Lymphoma What's Between Neoplastic Follicles Matters

We illustrate a rare case of coexisting extramedullary manifestation of CMML and new onset follicular lymphoma within the same core-needle biopsy of a lymph node. We discuss the differences between extramedullary hematopoiesis and extramedullary manifestation of myeloid neoplasms. We also highlight the importance of generous tissue sampling and thorough examination of nodal tissue in the setting of an established myeloid neoplasm to avoid missing rare but possible nodal involvement.

Renal Extramedullary Hematopoiesis Incidentally Detected on 18F-FDG PET/CT Imaging

ABSTRACT

18F-FDG PET/CT imaging of a 68-year-old woman with a known clinical diagnosis of systemic lupus erythematosus and recent-onset ataxia revealed FDG-avid soft tissue masses in bilateral renal sinuses and mildly increased bone marrow activity. Consecutive tissue sampling with fine-needle biopsy from renal sinus masses confirmed mass-forming extramedullary hematopoiesis corresponding to FDG-avid soft tissue lesions. Here we present a rare case of bilateral mass-forming extramedullary hematopoiesis at renal sinuses incidentally detected on 18F-FDG PET/CT imaging.

Paravertebral extramedullary hematopoiesis in a case of myelodysplastic syndrome with ring sideroblasts and an SF3B1 mutation

We present the case of a 56-year-old male patient with paravertebral extramedullary hematopoiesis (EMH) secondary to myelodysplastic syndrome with ring sideroblasts and multilineage dysplasia. In a routine health checkup over 5 years prior, he presented with asymptomatic mild anemia and a posterior mediastinal mass. Pathological and cytomorphological findings of the resected paravertebral mass were similar to those of his bone marrow specimen, and included cellularity with erythroid hyperplasia, multilineage dysplastic changes, and the presence of ring sideroblasts. A concordant SF3B1 mutation was detected in both bone marrow and paravertebral mass samples, suggesting that the EMH cells were derived from the bone marrow.

Neutrophil Homeostasis and Emergency Granulopoiesis: The Example of Systemic Juvenile Idiopathic Arthritis

Neutrophils are key pathogen exterminators of the innate immune system endowed with oxidative and non-oxidative defense mechanisms. More recently, a more complex role for neutrophils as decision shaping cells that instruct other leukocytes to fine-tune innate and adaptive immune responses has come into view. Under homeostatic conditions, neutrophils are short-lived cells that are continuously released from the bone marrow. Their development starts with undifferentiated hematopoietic stem cells that pass through different immature subtypes to eventually become fully equipped, mature neutrophils capable of launching fast and robust immune responses. During severe (systemic) inflammation, there is an increased need for neutrophils. The hematopoietic system rapidly adapts to this increased demand by switching from steady-state blood cell production to emergency granulopoiesis. During emergency granulopoiesis, the de novo production of neutrophils by the bone marrow and at extramedullary sites is augmented, while additional mature neutrophils are rapidly released from the marginated pools. Although neutrophils are indispensable for host protection against microorganisms, excessive activation causes tissue damage in neutrophil-rich diseases. Therefore, tight regulation of neutrophil homeostasis is imperative. In this review, we discuss the kinetics of neutrophil ontogenesis in homeostatic conditions and during emergency myelopoiesis and provide an overview of the different molecular players involved in this regulation. We substantiate this review with the example of an autoinflammatory disease, i.e. systemic juvenile idiopathic arthritis.

Extramedullary hematopoiesis in myeloproliferative neoplasms: Pathophysiology and treatment strategies

Extramedullary hematopoiesis (EMH) is often a physiologic response to ineffective marrow production of hematologic cells. While this can be found incidentally in various physiologic and pathophysiologic states, the myeloproliferative neoplasms (MPNs) are some of the most common underlying conditions found in patients with EMH. Although this process can assist with hematologic production in defective states, the burden of EMH can lead to symptomatic discomfort and mechanical obstructive complications, most commonly in the spleen and liver. Here we describe the pathophysiology of EMH, treatment options, including medical, surgical and radiation-based approaches.

Adult Hepatocellular Carcinoma Coexisting with Extramedullary Hematopoiesis

Extramedullary hematopoiesis (EMH) in adults usually occurs in the liver, spleen, and lymph nodes when bone marrow hematopoiesis fails. EMH has also been recognized in benign or malignant hepatic tumors, such as hepatoblastoma, hepatocellular adenoma, and vascular tumors. However, it is rarely encountered in hepatocellular carcinoma (HCC) in elderly adults, and the molecular mechanism of EMH in hepatic tumors remains unclear. We present a case of a 74-year-old man without any hematopoietic disorders and hepatitis viral infection who underwent hepatic resection for HCC. Histological examination revealed a well-differentiated HCC with trilineage hematopoiesis in the tumor and non-neoplastic liver. The coexistence of HCC and EMH in adult patients with no hematopoietic disorders is very rare and must be distinguished from poorly differentiated or dedifferentiated HCC and hepatoblastoma.

Obstructive Jaundice Secondary to Extramedullary Hematopoiesis

Extramedullary hematopoiesis (EMH) is the development of hematopoietic tissue outside of the bone marrow. In adults, the bone marrow is the main site of hematopoiesis. When this process occurs outside of the bone marrow, it is a sign of disease or deficiency. Clinically, the findings of EMH may be diverse. One rare complication that can arise from EMH is obstructive jaundice. This occurs when there is a blockage of bile flow leading to retention of bilirubin in hepatocytes. Identifying the markers of EMH and obstructive jaundice is important for optimizing positive outcomes. While often asymptomatic, EMH can be deadly if left untreated. In this case, we present a patient with obstructive jaundice secondary to EMH.

Extramedullary Hematopoiesis Presenting with Thoracic Spinal Cord Compression in a Young Adult with Thalassemia Major: A Case Report

BACKGROUND

Extramedullary hematopoiesis (EMH) refers to the production of blood cellular components at sites other than the bone marrow, namely liver, spleen, and lymph nodes. The common sites associated with this condition are the liver, spleen, and lymph nodes whereas the common conditions associated with it are myelofibrosis, myelodysplasia, thalassemia, sickle cell anemia, and polycythemia vera.

CASE DESCRIPTION

This report describes a young male with thalassemia major, who presented with symptomatic cord compression due to a thoracic intraspinal lesion. It was surgically excised and diagnosed as a case of EMH. The boy recovered fully and has been asymptomatic for six months now.

CONCLUSION

The occurrence of EMH in the thoracic spine is uncommon, whereas symptomatic cord compression as a result of it is even more unusual. Magnetic resonance imaging (MRI) is the diagnostic imaging of choice and treatment options that can be offered are surgical decompression, radiotherapy, hydroxyurea, and transfusion of packed red blood cells (RBCs).

An unusual diagnosis of paravertebral lesions: mediastinal myelolipoma

Background

Mediastinal myelolipoma is extremely rare. It is a benign nonfunctioning tumor composed of hematopoietic tissue and mature fatty tissue. Although computed tomography and magnetic resonance imaging are effective in diagnosing mediastinal myelolipoma, a definitive diagnosis is difficult to establish for rare extra-adrenal myelolipomas by imaging alone. Such tumors are often misdiagnosed as malignant retropleural liposarcoma, denoting a poor prognosis.

Case presentation: We herein describe a 72-year-old man with multiple bilateral paravertebral mediastinal myelolipomas and discuss the imaging findings and differential diagnoses. We used a computed tomography-guided core biopsy to attain a preoperative diagnosis. Using this technique, we avoided an unnecessary surgical procedure for the patient’s asymptomatic and relatively small lesions.

Conclusions

Instead of biopsy by lesion excision, we advocate conducting a precisely targeted, minimally invasive computed tomography-guided core biopsy to obtain a definitive preoperative diagnosis and thus avoid unnecessary surgery for mediastinal myelolipoma, a benign nonfunctioning tumor.

A 43-Year-Old Man With Rapidly Respiratory Failure and Spontaneous Massive Hemothorax

CASE PRESENTATION

A 43-year-old man urgently was referred to the hospital complaining of rapidly worsening dyspnea and right-side chest wall discomfort for 1 hour. Two hours later, he experienced acute respiratory failure that subsequently required intubation and invasive mechanical ventilation, thus he was transferred to ICU. He had no fever, weight loss, or bleeding tendency. He was previously healthy with no history of trauma and was not currently on any medication.

Invasive methods for the diagnosis and management of intrathoracic extramedullary hematopoiesis: A literature review

BACKGROUND

Extramedullary hematopoiesis is defined as hematopoiesis occurring outside of the bone marrow. It usually compensates insufficient bone marrow function or ineffective erythropoiesis and is observed mostly in hematological disorders. Most common locations of extramedullary hematopoiesis are the spleen, the liver and the lymph nodes. Intrathoracic extramedullary hematopoiesis is rare presenting as bilateral lobulated masses of lower paravertebral regions. This review summarizes the role of invasive techniques in the diagnosis and management of intrathoracic EMH and its complications.

METHODS

An electronic search in PubMed and Google Scholar was conducted with the keywords "intrathoracic extramedullary hematopoiesis" AND "surgery" OR "video-assisted thoracic surgery (VATS)" OR "medical thoracoscopy" OR "biopsy" OR "thoracotomy" OR "image-guided biopsy" OR "median sternotomy", within 1970 to 2020 with the limitation of English language to include those articles reporting data on invasive techniques in intrathoracic extramedullary hematopoiesis.

RESULTS

Overall, 93 articles were originally identified using our search criteria and from the reference list of the previously identified documents. Following elimination of duplicates, 29 were excluded after title, abstract or full text screening, since they did not report the use of invasive techniques in the diagnosis and management of intrathoracic extramedullary hematopoiesis.

CONCLUSIONS

Although in some cases radiological features are typical for the diagnosis of intrathoracic extramedullary hematopoeisis, invasive methods such as bronchoscopy with transbronchial biopsy, ιmage-guided fine needle aspiration, endobronchial ultrasound-guided fine needle aspiration of the mass and mediastinoscopy, medical thoracoscopy, median sternotomy, video-assisted thoracoscopic surgery and thoracotomy, are essential for definite diagnosis and management.

Extramedullary Hematopoiesis in Mismatch Repair Deficient Colon Cancer Patient on Adjuvant Chemotherapy

A 59-year-old male presented with a two-month history of abdominal pain and was found to have an obstructing cecal mass. Colonoscopy and biopsy confirmed invasive adenocarcinoma. Immunohistochemical analyses for mismatch repair (MMR) proteins revealed the loss of MLH1 as well as PMS2 in cancerous nuclei, which makes the tumor MMR deficient. Negative germline testing for MMR proteins ruled out the Lynch syndrome. After negative staging computerized tomography scan for distant metastases, he underwent ileocolectomy with ileotransverse colonic anastomosis. Final pathological analysis revealed poorly differentiated adenocarcinoma with signet ring features, negative margins, and 3/22 lymph nodes positive, classified as stage IIIB (T4aN1bM0). Adjuvant chemotherapy with modified FOLFOX (leucovorin calcium/folinic acid, fluorouracil, and oxaliplatin) was started without the use of any growth factor support. After cycle 9 of 12, he developed mild transaminitis, carcinoembryonic antigen elevation, and interval development of two heterogeneously enhancing hepatic lesions. Biopsy of both of these lesions revealed extramedullary hematopoiesis (EMH), with no evidence of metastatic disease. He completed adjuvant chemotherapy without complication, and these liver lesions have decreased in size during the follow-up period of almost two years thus far.

EMH is extremely rare in patients with colon cancer. Contributing factors include therapy-specific (growth factor support), bone marrow suppression secondary to chemotherapy and radiation therapy, and tumor-specific factors (cytokine and growth factors released by the tumor). To the best of our knowledge, this is the first case report of EMH in an MMR deficient colon cancer patient on adjuvant FOLFOX. MMR-deficient tumors show signs of a high degree of infiltration with CD8+ cytotoxic T lymphocytes as well as helper T cells, leading to increased production of cytokines, such as interferon-γ. This could be a potential etiology behind EMH in our patient who was MMR deficient. The role of the MMR-deficient state in the development of EMH should be explored further.

Primary myelofibrosis: 2021 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm (MPN) characterized by stem cell-derived clonal myeloproliferation that is often but not always accompanied by JAK2, CALR, or MPL mutations. Additional disease features include bone marrow reticulin/collagen fibrosis, aberrant inflammatory cytokine expression, anemia, hepatosplenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

Bone marrow morphology is the primary basis for diagnosis. Presence of JAK2, CALR, or MPL mutation, expected in around 90% of the patients, is supportive but not essential for diagnosis; these mutations are also prevalent in the closely related MPNs, namely polycythemia vera (PV) and essential thrombocythemia (ET). The 2016 World Health Organization classification system distinguishes "prefibrotic" from "overtly fibrotic" PMF; the former might mimic ET in its presentation. Furthermore, approximately 15% of patients with ET or PV might progress into a PMF-like phenotype (post-ET/PV MF) during their clinical course.

ADVERSE MUTATIONS

SRSF2, ASXL1, and U2AF1-Q157 mutations predict inferior survival in PMF, independent of each other and other risk factors. RAS/CBL mutations predicted resistance to ruxolitinib therapy.

ADVERSE KARYOTYPE

Very high risk abnormalities include -7, inv (3), i(17q), +21, +19, 12p-, and 11q-.

RISK STRATIFICATION

Two new prognostic systems for PMF have recently been introduced: GIPSS (genetically-inspired prognostic scoring system) and MIPSS70+ version 2.0 (MIPSSv2; mutation- and karyotype-enhanced international prognostic scoring system). GIPSS is based exclusively on mutations and karyotype. MIPSSv2 includes, in addition, clinical risk factors. GIPSS features four and MIPSSv2 five risk categories.

RISK-ADAPTED THERAPY

Observation alone is advised for MIPSSv2 "low" and "very low" risk disease (estimated 10-year survival 56%-92%); allogeneic hematopoietic stem cell transplant (AHSCT) is the preferred treatment for "very high" and "high" risk disease (estimated 10-year survival 0%-13%); treatment-requiring patients with intermediate-risk disease (estimated 10-year survival 30%) are best served by participating in clinical trials. In non-transplant candidates, conventional treatment for anemia includes androgens, prednisone, thalidomide, and danazol; for symptomatic splenomegaly, hydroxyurea and ruxolitinib; and for constitutional symptoms, ruxolitinib. Fedratinib, another JAK2 inhibitor, has now been FDA-approved for use in ruxolitinib failures. Splenectomy is considered for drug-refractory splenomegaly and involved field radiotherapy for non-hepatosplenic EMH and extremity bone pain.

NEW DIRECTIONS

A number of new agents, alone or in combination with ruxolitinib, are currently under investigation for MF treatment (ClinicalTrials.gov); preliminary results from some of these clinical trials were presented at the 2020 ASH annual meeting and highlighted in the current document.

Lenograstim-Induced Nodal Extramedullary Hematopoiesis: A Challenging Diagnosis in Lymphoma Evaluation With 18F-FDG PET/CT

We report the case of a 23-year-old man with nodal EMH (extramedullary hematopoiesis) occurring during treatment for a stage IIA "gray-zone" lymphoma. Although it is often related to myeloproliferative bone marrow disease, benign etiologies such as lenograstim treatment after chemotherapy can also induce EMH and be responsible for false-positive F-FDG PET/CT examinations. In this respect, GLUT overexpression in hematopoietic lineages and macrophages of the inflammatory environment are responsible for increased F-FDG uptake. Histopathologic confirmation of new hypermetabolic lesions on follow-up PET/CT may be required when the new lesions do not conform with the treatment responses in the preexisting lesions.

Myeloid diseases in the lung and pleura

Myeloid diseases detected as primary or secondary lesions in the lung and pleura are rare. Clinical presentations and radiographic results may vary significantly depending on the nature of the diseases. The most common diseases associated with lung and pleura involvement are myeloid sarcoma/acute myeloid leukemia (AML) and extramedullary hematopoiesis (EMH). AML typically represents localized involvement by systemic acute leukemia, while EMH is frequently secondary to underlying benign hematolymphoid disorders or myeloproliferative neoplasms. This review provides an overview of the pathogenesis, clinical presentations, radiologic/imaging studies, pathologic and genetic findings, and treatment/outcomes associated with myeloid diseases in the lung and pleura.

Generation of Myeloid Cells in Cancer: The Spleen Matters

Myeloid cells are key components of the tumor microenvironment and critical regulators of disease progression. These innate immune cells are usually short-lived and require constant replenishment. Emerging evidence indicates that tumors alter the host hematopoietic system and induce the biased differentiation of myeloid cells to tip the balance of the systemic immune activities toward tumor-promoting functions. Altered myelopoiesis is not restricted to the bone marrow and also occurs in extramedullary organs. In this review, we outline the recent advances in the field of cancer-associated myelopoiesis, with a focus on the spleen, the major site of extramedullary hematopoiesis in the cancer setting. We discuss the functional specialization, distinct mechanisms, and clinical relevance of cancer-associated myeloid cell generation from early progenitors in the spleen and its potential as a novel therapeutic target.

Multi-focal Lytic Lesions in a Patient with Myelofibrosis: A Case Report

Myelofibrosis is a rare disorder that is classified as one of the myeloproliferative disorders. This particular disorder results in the abnormal proliferation of hematopoietic stem cells in the bone marrow. In some cases, such as ours, pathologic fractures can occur due to skeletal manifestations. We report on a rare finding of rapidly progressive lytic lesions in multiple regions throughout the body. This presentation of myelofibrosis behaving in a metastatic-like fashion has not been previously described.

Marrow outside marrow: imaging of extramedullary haematopoiesis

Extramedullary haematopoiesis (EMH) refers to the formation of non-neoplastic blood cell lines outside the bone marrow and is a common incidental finding when patients with haematological disorders are imaged. EMH presenting as mass (tumefactive EMH) has long been a radiological conundrum as it resembles neoplasms. Several imaging findings have been described in EMH, and these vary depending on the activity of the underlying haematopoiesis. The older lesions are easier to diagnose as they often demonstrate characteristic findings such as haemosiderin and fat deposition. In comparison, the newer, actively haematopoietic lesions often mimic neoplasms. Molecular imaging, particularly ^99mTc labelled sulphur colloid scintigraphy, may be helpful in such cases. Although imaging is extremely useful in detecting and characterising EMH, imaging alone is often non-diagnostic as no single mass shows all the typical findings. Hence, a judgement based on the clinical background, combination of imaging findings, and slow interval growth may be more appropriate and practical in making the correct diagnosis. In every case, an effort has to be made in providing an imaging-based diagnosis as it may prevent a potentially risky biopsy. When confident differentiation is not possible, biopsy has to be resorted to. This article describes the causes, pathophysiology, and theories underlying the genesis of EMH, followed by the general and location-specific imaging findings. The purpose is to provide a thorough understanding of the condition as well as enable the clinical radiologist in making an imaging-based diagnosis whenever possible and identify the situations where biopsy has to be performed.

A case report of a rare omental extramedullary hematopoiesis in an adult: 'an idiopathic finding'

This is a case of a 62-year-old female, known to have multiple medical problems, who presented to her primary care physician with an intermittent abdominal pain and discomfort for a few months. The initial work-up showed mild leucocytosis and a small mass in the omentum. Given that the most concerning differential diagnosis was malignancy, the patient was referred to oncology, where biopsy of the mass showed omentum extramedullary hematopoiesis. The differential diagnosis was wide; however, a repeat computed tomography (CT) scan of the abdomen and pelvis did show persistence of the omental mass. After ruling out any possible causes, including myelofibrosis, with a normal bone marrow, her extramedullary hematopoiesis was deemed of unknown origin and with no clear explanation. Therefore, the patient was diagnosed with a rare adult idiopathic omental extramedullary hematopoiesis that was stable over time.

Extramedullary hematopoiesis: Clinical and cytological features

INTRODUCTION

Hematopoiesis usually occurs in bone marrow in adults and when it occurs at sites except for bone marrow, it is termed as extramedullary hematopoiesis (EMH). It is usually found in organs, which are vigorously involved in fetal hematopoiesis, including liver, spleen, and lymph nodes. FNAC is easy and rapid method to diagnose EMH.

AIM

To study the spectrum of extramedullary hematopoiesis (EMH) on fine-needle aspiration cytology (FNAC).

MATERIAL AND METHODS

A total of 10 patients who were diagnosed with EMH on FNAC were studied over a period of 5.5 years. Smears were stained with May Grunwald Giemsa (MGG) and Hematoxylin and Eosin (H and E). The detailed clinical and cytomorphological spectrum of EMH were studied.

RESULTS

The mean age of the patient was 42.5 years, with age ranging between 14 and 78 years. The commonest site of EMH was lymph node (n = 8, 80%) followed by paravertebral area (n = 2, 20%). Clinical diagnosis was EMH in just one case. Mean hemoglobin of the patient was 7.9 g/L. Bone marrow examination was available in 6 cases. On FNAC, we saw variable mixture of bone marrow elements including megakaryocytes (2.6%, 0-6%), myelocytes and metamyelocytes (29.2%, 18-33%), erythroid precursors (3.2%, 0-7%), polymorphs (21.7%, 10-36%), blasts (1.1%, 0-4%), eosinophils (2.5%, 0-7%), and lymphocytes (39.7%, 21-60%).

CONCLUSION

Cytopathologists must be alert of the clinical as well as cytological spectrum of extramedullary hematopoiesis for greater accuracy in diagnosis and to escape pitfalls in its diagnosis.

A large intrathoracic extramedullary hematopoiesis in alpha-thalassemia: A case report

RATIONALE

Extramedullary hematopoiesis (EMH) is a rare disease characterized by the formation of hematopoietic elements outside the bone marrow driven by several hematological disease. To the best of our knowledge, EMH is relatively common in patient with beta-thalassemia or hereditary spherocytosis but rarely reported in patients with alpha-thalassemia. Here, we discuss a large intrathoracic EMH (measuring 95 mm × 66 mm) without presenting severe complications in alpha-thalassemia along with literature review.

PATIENT CONCERNS

A 55-year-old Chinese female patient with alpha-thalassemia presented with ipsilateral pleural effusion and low hemoglobin level.

DIAGNOSIS

Lung cancer was suspected at first and the mass was subjected to CT-guided percutaneous mediastinum biopsy and the pathology confirmed the final diagnosis of extramedullary hematopoiesis.

INTERVENTIONS

Blood transfusion, thoracentesis and regular follow up were scheduled rather than surgical interventions or radiotherapy since our patient did not exhibit significant symptoms.

OUTCOMES

After 6 months' regular follow up, the patient exhibited no evidence of disease progress.

LESSONS

EMH is frequently misdiagnosed and should be differentiated from other masses in thoracic cavity, especially when the underlying hematological disease is discovered. Treatment methods of EMH include surgical resection, hyper-transfusion, hydroxyurea, low-dose radiation or a combination of them.

Extramedullary hematopoiesis masquerading as a cranial (clivus) tumor

Extramedullary hematopoiesis (EMH) is a well-known phenomenon occurring during fetal development. In the postfetal condition, EMH is commonly associated with hematologic conditions including chronic myeloproliferative or lymphoproliferative disorders, leukemias, and chronic and inherited anemias. We report an unusual location for EMH that masqueraded as a cranial tumor.

[Lung involvement in hematologic systemic diseases]

Pulmonary diseases can occur across the entire disease spectrum of malignant hematologic systemic diseases. Although infectious processes of the lungs are common in these immunosuppressed patient collectives, noninfectious causes account for up to half of the pulmonary manifestations found in hematologic malignancies. Besides the frequent infections including opportunistic pathogens, a broad differential diagnosis including drug-induced lung injury by cytostatic substances, cytokines, and innovative immunotherapeutic agents, rarer transfusion of blood products and intrathoracic manifestations of the hematologic malignancy itself, have to be kept in mind. Finally, vascular complications can also lead to pulmonary reactions. Early and consistent diagnostics and treatment of the bronchopulmonary, intrathoracic and vascular complications within the framwework of hematologic systemic diseases can be essential for the patient's prognosis.

A case report of extramedullary haematopoiesis within left ventricle myocardium and apical thrombus in acute heart failure: diagnosis, treatment, and long-term outcome

Background 

Extramedullary haematopoiesis (EMH) within myocardium is a rare phenomenon, and its occurrence in left ventricle myocardium or apical thrombus of a young female has never been reported.

Case summary 

A 23-year-old active female with progressive worsening of dyspnoea. A transthoracic echocardiogram demonstrated a left ventricular ejection fraction of 10–15% and apical thrombus. Bilateral upper extremity Doppler showed deep venous thrombus in the left arm and superficial vein thrombus in both arms. She had reduced activity of antithrombin III, deficiency of protein C and S. Computed tomography of the head showed right thalamic infarct. Having failed optimal medical therapy, rapidly worsening of symptoms (New York Heart Association Class IV and clinical Class C) and cardiogenic shock, she underwent HeartWare^® left ventricular assist device (LVAD) placement as a bridge to heart transplant. Intraoperative apical thrombus was carefully extracted while maintaining adequate anticoagulation with heparin infusion. Pathology report of the excised apical myocardium and thrombus demonstrated haematopoietic cells. Twenty-six months since LVAD implantation, she remains active and Status 7 on transplant list (due to body mass index) without any further episodes of thromboembolic events.

Discussion

We report an unprecedented case of an active young female with EMH within left ventricular myocardium and apical thrombus. Although redirected differentiation and embolic haematopoietic cells seem to explain this phenomenon, the exact pathophysiology remains unknown. Despite having pre-existing apical thrombus and acute deep vein thrombus, the key towards success was meticulous extraction of apical thrombus while preserving inherent trabecular architecture and adequate anticoagulation.

Nonanemic extramedullary hematopoiesis in the posterior mediastinum

Extramedullary hematopoiesis is a rare condition characterized by the formation of blood cells outside the bone marrow. It is commonly seen in patients with hematopoietic disorders or chronic anemia. Here, we report the case of a 55-year-old patient who had extramedullary hematopoiesis that manifested as an asymptomatic posterior mediastinal mass. Chest computed tomography showed a 30 × 35-mm mass located on the left side of the D11 vertebra. Laboratory investigations revealed no signs of anemia. The tumor was safely and completely removed using video-assisted thoracoscopic surgery. Pathological studies confirmed the extramedullary hematopoiesis nature of the tumor.

A 54-year-old Woman with Myelofibrosis and Massive Hemothorax Due to Primary Extramedullary Hematopoiesis of the Pleura

Extramedullary hematopoiesis, which represents ectopic blood cell production, is usually an incidental finding accompanying hematologic pathology. The liver and spleen are the most common sites of extramedullary hematopoiesis, but thoracic involvement is likewise observed. Pleural effusions in the setting of intrathoracic extramedullary hematopoiesis have been attributed to mechanical interactions between the pleural surface and neighboring paravertebral masses consisting of hematopoietic tissue. Rupture of these highly vascularized lesions into the adjacent pleural space has been the putative mechanism in cases complicated by hemothorax. Histologically proven instances of islets of extramedullary hematopoiesis occurring on the pleural surface itself are exceedingly rare. Our case of a patient with myelofibrosis and massive pleural effusion is only the third such example described in the literature and the second to result in a confirmed hemothorax requiring surgery. As expected, technetium-99m sulfur (Tc-99m sulfur) colloid scanning accurately localized sites of extramedullary hematopoiesis in our patient, and there was a salutary response to radiation therapy.