Massive intrahepatic extramedullary hematopoiesis in myelofibrosis

Magnetic resonance imaging features of intrahepatic extramedullary hematopoiesis: Three case reports

BACKGROUND

Extramedullary hematopoiesis rarely occurs within the liver alone, and is easily misdiagnosed. The radiological literature on this disease is exclusively case reports. There is a paucity of literature on the role of magnetic resonance imaging (MRI). The most common imaging modalities used are computed tomography and ultrasound. This report aims to provide more data on the appearance of extramedullary hematopoiesis using MRI to help radiologists establish the diagnosis.

CASE SUMMARY

Three patients (one male and two females) were incidentally found to have a hepatic mass or nodule, without hepatomegaly or splenomegaly. Laboratory tests including liver function, serum hepatic tumor markers, and hepatitis serologic markers were normal. On MRI scans, all lesions showed lower signal intensity on in-phase images than on out-phase images. One case showed changes in signal intensity on T2 weighted images (WI) and diffusion WI, which shifted from hyperintensity to hypointensity with size enlargement between two rounds of imaging examination. These lesions exhibited different enhancement patterns on dynamic contrast enhancement series.

CONCLUSION

The MRI signal change and in-/out-phase image might provide useful information and help radiologists establish the diagnosis of intrahepatic extramedullary hematopoiesis.

Extramedullary haematopoiesis presenting as a periportal mass

Extramedullary haematopoiesis (EMH) is defined as haematopoiesis occurring in organs outside the bone marrow. The liver is one of the rare sites of EMH, and to the best of our knowledge, a few cases of adult EMH of the liver have been reported in the last 20 years. Here, we reported the case of a 68-year-old man with a known history of myelofibrosis presented with vague abdominal pain. An abdominal CT scan showed a hypoattenuating periportal mass encasing the portal vein. The final diagnosis of EMH was made through the histopathological examination. This is a rare presentation of EMH, which may be easily mistaken for other pathologies such as metastases. Familiarity with this type of presentation aids in correctly diagnosing it in an appropriate clinical setting.

Functional integration of acute myeloid leukemia into the vascular niche

Vascular endothelial cells are a critical component of the hematopoietic microenvironment that regulates blood cell production. Recent studies suggest the existence of functional cross-talk between hematologic malignancies and vascular endothelium. Here, we show that human acute myeloid leukemia (AML) localizes to the vasculature in both patients and in a xenograft model. A significant number of vascular tissue-associated AML cells (V-AML) integrate into vasculature in vivo and can fuse with endothelial cells. V-AML cells acquire several endothelial cell-like characteristics, including the up-regulation of CD105, a receptor associated with activated endothelium. Remarkably, endothelial-integrated V-AML shows an almost 4-fold reduction in proliferative activity compared to non-vascular associated AML. Primary AML cells can be induced to down regulate the expression of their hematopoietic markers in vitro and differentiate into phenotypically and functionally-defined endothelial-like cells. After transplantation, these leukemia-derived endothelial cells are capable of giving rise to AML. Taken together, these novel functional interactions between AML cells and normal endothelium along with the reversible endothelial cell potential of AML suggest that vascular endothelium may serve as a previously unrecognized reservoir for acute myeloid leukemia.

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.

CT and MR findings in extramedullary haematopoiesis with biliary system encasement: a case report

Extramedullary haematopoiesis is the production of blood elements outside the bone marrow cavity. In our case computed tomography and magnetic resonance imaging revealed the presence of a rare localization of extramedullary haematopoiesis with encasement of the biliary system in a 59 years-old male Caucasian patient, with chronic myelofibrosis and hepatic failure's symptomatology. Computed tomography detected the presence of homogeneous hypodense tissue around intra-hepatic bile ducts with minimal contrast enhancement, strongly suggestive for extramedullary haematopoiesis. Magnetic resonance confirmed the presence of a solid tissue surrounding the biliary tree, showing late enhancement after gadolinium administration suggestive for non-active lesion of extramedullary haematopoiesis. Final diagnosis was established by percutaneous biopsy.

Intrahepatic extramedullary hematopoiesis mimicking a hypervascular hepatic neoplasm on dynamic- and SPIO-enhanced MRI

We present a rare case of a focal intrahepatic extramedullary hematopoiesis (EMH) that mimicked a hypervascular hepatic neoplasm in a 33-year-old woman with idiopathic myelofibrosis. The lesion showed homogeneous and persistent enhancement on both contrast-enhanced CT and gadolinium-enhanced dynamic MR imaging. The lesion did not demonstrate an apparent signal drop on a T2^*-weighted sequence following administration of a superparamagnetic iron-oxide agent (SHU 555A). A hepatocellular adenoma was the initial radiological diagnosis. To the best of our knowledge, this is the first report of a histopathologically proven intrahepatic EMH evaluated with dynamic- and SPIO-enhanced MRI.

MRI features of intrahepatic extramedullary haematopoiesis in sickle cell anaemia

Extramedullary haematopoiesis (EMH) is a reactive mechanism by which blood cells are produced outside of the bone marrow to supplement insufficient production or increased destruction of erythrocytes. EMH is uncommon in sickle cell anaemia (SCA). We report the first case of focal intra-hepatic EMH in SCA depicted on MRI occurring in a 32-year-old woman with homozygote SCA and in view of previously published data, highlight the diagnostic features suggesting a differential diagnosis with other focal liver lesions including infectious, inflammatory or primary liver tumors.

[Role of stem cells in adult hepatic regeneration]

Central to the successful surgically treatment numerous liver diseases is the ability of the organ to regenerate. The understanding of the process of self-renewal has both changed and progressed over the last few decades. For many years, the assumption was that the liver regenerates primarily through the division of mature liver cells. However, over the last few years there has been increasing evidence of the participation of stem cells. Intrahepatic stem cells, so-called oval cells, are activated under conditions of severe or chronic liver disease and originate from the canals of Hering. In addition, extrahepatic stem cells may migrate from the bone marrow into the liver when the regenerative capacity of the liver itself is depleted. It is not yet fully clear how the different stem cell populations interact with both each other and the mature liver cell population to achieve homeostatic cell and differentiation equilibrium in the diseased and/or regenerating organ. In any case, the outstanding growth potential of liver stem cells may become a clinically viable option in the field of cell transplantation.

Extramedullary hematopoiesis presenting as a focal splenic mass: a case report

We report the ultrasound, computed tomographic, and magnetic resonance imaging findings in a case of extramedullary hematopoiesis presenting as a focal splenic mass in a patient with myelodysplastic syndrome. Ultrasound demonstrated a well-circumscribed hyperechoic mass, whereas computed tomography showed a heterogeneous mass better visualized after administration of intravenous contrast. On magnetic resonance imaging, the lesion was hypointense to the spleen on T1-weighted images, with increased signal on T2-weighted images, and demonstrated enhancement after intravenous contrast administration. Extramedullary hematopoiesis should be considered in the differential diagnosis for a splenic mass in any patient with a hematologic disorder.

Idiopathic myelofibrosis with nodal, serosal and parenchymatous infiltration. Case report and review of the literature

Idiopathic myelofibrosis (IMF) is a breakpoint cluster region rearrangement-negative chronic myeloproliferative disease with progressive bone marrow fibrosis. We report a female patient (65 years old) who was admitted to our hospital in 1996. Trephine bone marrow biopsy revealed diffuse fibrosis with atypical multilobulated megakaryocytes. A cellular phase of IMF was diagnosed. Three years later, despite being at intermediate risk, the patient developed generalized lymphadenopathy and multiple sclerosing tumors throughout the peritoneum and retroperitoneum. Biopsy specimens from these tumors revealed sclerosing hematopoietic infiltrates. The present case demonstrates that IMF not only can progress to acute leukemia but can also spread uncontrollably, or 'metastasize' with extensive sclerosing hematopoietic tumors throughout the body.