Kapasiform Hemangioendothelioma (KHE)





Kaposiform Hemangioendothelioma (KHE): This is a vascular tumor associated with the Kasabach-Merritt phenomenon (severe coagulopathy due to platelet trapping and spontaneous bleeding). These tumors are histopathologically distinct from the common hemangiomas of infancy. 

KHE may be present at birth in neonates, or they can develop in infants within the first few months after birth. An ill-defined purpuric mass is a common presentation. A truncal location is the most common site. Destructive bone changes in adjacent bones are common. 

Diagnosis: The MRI findings of Kaposiform hemangioendothelioma also clearly differ from those of common infantile hemangioma. In contrast to common hemangioma, this neoplastic birthmark characteristically involves multiple tissue planes, with cutaneous thickening, subcutaneous stranding, and edema. Gradient-echo images may demonstrate hemosiderin. Superficial feeding and draining vessels are less frequent and less prominent than with common hemangioma. Destructive osseous changes in the adjacent bones are common in Kaposiform hemangioendothelioma, whereas only some remodeling occasionally occurs in infantile hemangiomas.

Photo#1 shows a relatively small kaposiform hemangioendothelioma near the ear. Figure#2 is a catheter arteriogram in apatient with a large kaposiform hemangioendothelioma in the thigh. Figure#3 is a T2 weighted axial MRI image shows an ill defined infiltrative appearing kaposiform hemangioendothelioma lesion in the upper thigh and buttock area.



1st image is histopathology of Kaposiform hemangioendothelioma (Source: PathoPic). 2nd image is a T2 weighted MR image demonstrating a large inhomogeneous soft tissue abnormality (tumor) in the facial area (kaposiform hemangioendothelioma). This patient developed Kasabach-Merritt syndrome, required multiple embolization procedures.  

Treatment:  Kaposiform hemangioendothelioma has a mortality rate of 24%, which is related to coagulopathy or complications of local tumor infiltration. The tumor is associated with extremely low platelet counts and markedly decreased fibrinogen levels. Patients with Kaposiform hemangioendothelioma need to be closely monitored for severe coagulopathy. Pharmacological treatment regimen is similar to that of infantile hemangioma depending on the severity of the condition. Other treatment alternatives for patients with kaposiform hemangioendothelioma are transcatheter embolization and surgical excision. 




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