Bone and soft tissue Case 3. Painful knee mass from a middle-aged patient.

•Diagnosis: epithelioid hemangioendothelioma (EHE)

•Great variability in clinical behavior and prognosis, occurs in patients of wide age range, and at both superficial and deep locations.

•Positive for cytokeratin and endothelial markers CD34, CD31 and ERG

•Recurrent WWTR1-CAMTA1 fusion

•Variant EHE with YAP1-TFE3 fusion. See next two pictures from Dr. Christina Antonescu.