The role of T2*-weighted gradient echo in the diagnosis of tumefactive intrahepatic extramedullary hematopoiesis in myelodysplastic syndrome and diffuse hepatic iron overload: a case report and review of the literature

Abstract Background Extramedullary hematopoiesis is the proliferation of hematopoietic cells outside bone marrow secondary to marrow hematopoiesis failure. Extramedullary hematopoiesis rarely presents as a mass-forming hepatic lesion; in this case, imaging-based differentiation from primary and metastatic hepatic neoplasms is difficult, often leading to biopsy for definitive diagnosis. We report a case of tumefactive hepatic extramedullary hematopoiesis in the setting of myelodysplastic syndrome with concurrent hepatic iron overload, and the role of T2*-weighted gradient-echo magnetic resonance imaging in differentiating extramedullary hematopoiesis from primary and metastatic hepatic lesions. To the best of our knowledge, T2*-weighted gradient-echo evaluation of extramedullary hematopoiesis in the setting of diffuse hepatic hemochromatosis has not been previously described. Case presentation A 52-year-old white man with myelodysplastic syndrome and marrow fibrosis was found to have a 4 cm hepatic lesion on ultrasound during workup for bone marrow transplantation. Magnetic resonance imaging revealed diffuse hepatic iron overload and non-visualization of the lesion on T2* gradient-echo sequence suggesting the presence of iron deposition within the lesion similar to that in background hepatic parenchyma. Subsequent ultrasound-guided biopsy of the lesion revealed extramedullary hematopoiesis. Six months later, while still being evaluated for bone marrow transplant, our patient was found to have poor pulmonary function tests. Follow-up computed tomography angiogram showed a mass within his right main pulmonary artery. Bronchoscopic biopsy of this mass once again revealed extramedullary hematopoiesis. He received radiation therapy to his chest. However, 2 weeks later, he developed mediastinal hematoma and died shortly afterward, secondary to respiratory arrest. Conclusions Mass-forming extramedullary hematopoiesis is rare; however, our report emphasizes that it needs to be considered in the initial differential diagnosis of hepatic lesions arising in the setting of bone marrow disorders. We also show that in the setting of diffuse hepatic iron overload, tumefactive extramedullary hematopoiesis appeared isointense to background liver on T2* gradient-echo sequence, while adenoma, hepatoma, and hepatic metastasis appear hyperintense. Thus, T2*-weighted gradient-echo sequence may have a potential role in the imaging diagnosis of mass-forming hepatic extramedullary hematopoiesis arising in the setting of diffuse iron overload

Recombinant tumor necrosis factor and immune interferon act singly and in combination to reorganize human vascular endothelial cell monolayers.

Human endothelial cells (HECs) in confluent primary culture reproduce the epithelioid organization of the vascular lining in situ. The addition of greater than or equal to 20 U/ml recombinant tumor necrosis factor (rTNF) or greater than or equal to 16 U/ml recombinant immune interferon (rIFN-gamma) causes HECs 1) to become elongated, 2) to overlap, 3) to rearrange their actin filaments, and 4) to lose their stainable fibronectin matrix. These changes develop over 72-96 hours and are reversible upon withdrawal of the mediator. In serially passaged HECs similar morphologic changes develop. Furthermore, rTNF and rIFN-gamma are each cytostatic for subconfluent passaged cultures. When added in combination, low concentrations of rTNF and rIFN-gamma act synergistically, whereas higher concentrations (eg, 100 U/ml rTNF and 200 U/ml rIFN-gamma) produce unique morphologic changes. Doubly treated primary HECs extend many long, overlapping, spinelike processes and expose the substratum. Doubly treated passaged HECs become extremely elongated and then shed in large numbers. These in vitro changes in endothelial cell morphology and behavior may underlie immunologically mediated vascular responses in vivo