Kaposiform Hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that primarily affects infants and young children. Unlike common hemangiomas, KHE is known for its association with Kasabach-Merritt phenomenon (KMP), a life-threatening condition characterized by thrombocytopenia and coagulopathy. Understanding KHE’s symptoms, diagnosis, and treatment options is crucial for early intervention and better outcomes.
What Is Kaposiform Hemangioendothelioma?
Kaposiform Hemangioendothelioma is a rare vascular neoplasm that originates from endothelial cells. It is classified as an intermediate malignancy due to its potential to cause severe complications, although it does not metastasize. KHE most commonly presents in infancy but has been reported in older children and adults.
Symptoms of Kaposiform Hemangioendothelioma
- Firm, purplish skin lesion – Often appears on the extremities, trunk, or retroperitoneum
- Progressive enlargement – Tumor tends to grow over time
- Pain and swelling – Due to infiltration into surrounding tissues
- Kasabach-Merritt phenomenon (KMP) – A critical complication leading to severe thrombocytopenia, coagulopathy, and potential hemorrhage
- Lymphedema – Occurs when the tumor affects lymphatic drainage
Causes and Risk Factors
The exact cause of KHE remains unknown, though it is believed to result from genetic and environmental factors. Some studies suggest a role of somatic mutations in angiogenesis-related genes.
Diagnosis of Kaposiform Hemangioendothelioma
1. Clinical Examination
Physicians evaluate the lesion’s appearance, growth pattern, and associated symptoms.
2. Imaging Studies
- Ultrasound with Doppler – Helps assess vascular involvement
- MRI with contrast – Gold standard for detecting soft tissue extension
- CT scan – Used in cases where internal organ involvement is suspected
3. Histopathology
A biopsy is performed for definitive diagnosis. KHE exhibits spindle-shaped endothelial cells and lobular architecture with lymphatic vessel infiltration.
4. Laboratory Tests
- Platelet count – Thrombocytopenia indicates Kasabach-Merritt phenomenon
- Coagulation profile – Prolonged PT and aPTT suggest clotting abnormalities
- D-dimer levels – Elevated in severe cases
Treatment Options for Kaposiform Hemangioendothelioma
1. Medical Therapy
- Sirolimus (mTOR inhibitor) – Considered first-line treatment for KHE and KMP due to its antiangiogenic effects
- Corticosteroids – High-dose prednisolone is often used but has variable efficacy
- Vincristine – Effective in severe cases unresponsive to sirolimus
2. Supportive Care
- Platelet transfusions – Necessary for severe thrombocytopenia
- Anticoagulation management – To control coagulopathy and prevent bleeding
3. Surgical Intervention
Surgery is reserved for cases where the tumor is well-defined and resectable without high risk of recurrence or complications.
4. Embolization and Laser Therapy
- Embolization – Used to shrink tumors by blocking blood supply
- Laser therapy – In select superficial cases to reduce lesion size
Prognosis and Long-Term Outlook
The prognosis of KHE depends on early diagnosis and treatment. With proper management, many cases show tumor regression and improved platelet counts. However, patients with severe KMP remain at risk for complications and require long-term follow-up.
Kaposiform Hemangioendothelioma is a rare but potentially life-threatening vascular tumor. Timely diagnosis and appropriate treatment—especially the use of sirolimus and supportive therapies—significantly improve outcomes. Continued research and clinical trials are essential to refine treatment strategies and enhance patient care.
