Introduction Hemangioendothelioma (or epitheliod hemangioendothelioma in soft tissue) is considered a rare sarcoma showing endothelial differentiation distinct histologically and molecularly from benign hemangioma and high-grade angiosarcoma Epidemiology demographics occurs most commonly in 4th - 5th decade women affected more than men location more commonly in soft-tissue > bone usually occurs in the lower extremity risk factors exposure to arsenic Pathophysiology pathoanatomy arise from the lining of blood vessels cellular biology stratifed into two groups based on size of tumor and mitotic activity classic malignant Prognosis natural history of disease malignant tumor > 3cm and >3 mitoses/50 HPFs have 5 year survival of 59% classic 100% survival if lack these features prognostic features 20 - 30% of tumors metastasize visceral involvement is considered the most important criterion in predicting survival Presentation Symptoms local pain not usually associated with swelling Imaging Radiographs recommended views 2 or 3 views of affected bone findings lytic lesion with no reactive bone areas of cortical destruction and cortical expansion are common CT indication cross-sectional imaging to better define the area of concern findings multifocal eccentric lytic lesions in bone matrix mineralization may be present calcification and periosteal reaction is rare MRI indication cross-sectional imaging to better define the area of concern findings high signal intensity on T2-weighted images edematous bone reaction surrounding the lesion Histology Macroscopic angiocentric growth expanding the vessel wall obliterating the lumen and spreading centrifugally into surrounding tissue induce a sclerotic response Microscopic arranged in single files, cords and small nests typically lack well-formed vascular channels, with only immature, intracytoplasmic lumina Differential diagnosis Langerhans cell histiocytosis (LCH), angiosarcoma, infection, myeloma, metastasis, and lymphoma the diagnosis of hemangioednthelioma requires histopathologic analysis Treatment Nonoperative radiation therapy alone indications low grade lesion (classic) chemotherapy the role of chemotherapy is not yet clear Operative surgical resection +/- radiotherapy indications high grade lesion (malignant) Ibank Location Xray Xray CT B. Scan MRI MRI Histo(1) Case A tibia Case B finger Case C tibia Case D tibia (1) - histology does not always correspond to clinical case