Epithelioid Hemangioendothelioma

Epithelioid hemangioendothelioma is a rare, well-differentiated vascular tumor characterized by endothelial cells having an epithelioid appearance (abundant eosinophilic cytoplasm and a rounded or slightly fusiform shape). Epithelioid hemangioendothelioma can occur in bone, lung, and liver.

Epithelioid hemangioendotheliomas belong to the group of vascular tumors that includes benign epithelioid hemangioma on one end of the spectrum and its malignant counterpart, epithelioid angiosarcoma, on the other, all of which have a tendency to develop multifocal disease.

Epithelioid hemangioendothelioma has been called low-grade anaplastic angiosarcoma, cellular hemangioma, histiocytoid hemangioma, and angioendothelioma. It has a peak incidence during the second and third decades of life and tends to affect males more often than females.

The clinical presentation is nonspecific and consists of pain and occasional swelling. Pathologic fractures are uncommon. Multicentric disease is seen in about half of cases. When multiple, they have a tendency to involve a single anatomic region or extremity.

Epithelioid hemangioendotheliomas most commonly affect the long tubular bones of the lower limb, followed by the pelvis, vertebral bodies, ribs, small bones of the feet, and long tubular bones of the upper extremity.

Classically, they appear as poorly marginated lytic lesions commonly with areas of cortical destruction and expansion. Occasionally the lesions may have a coarse trabeculated or honeycomb pattern that suggests a vascular nature. Matrix mineralization can be seen in some cases. Well-defined lesions with or without surrounding sclerosis may be seen, but aren't common. A soft tissue mass is seen in less than 50% of cases.

Differential considerations for multiple lytic lesions in a young patient include Langerhanscell histiocytosis, giant cell tumors, fibrous dysplasia, lymphoma, and metastatic disease. In older patients, metastases and myeloma would be more common. The finding of multiple lytic lesions in a regional distribution, should suggest the diagnosis.

The images above are from an elderly patient with multiple lytic lesions in the right lower extremity.

References

• Adler B, Naheedy J, Yeager N, Nicol K, Klamar J. Multifocal epithelioid hemangioendothelioma in a 16-year-old boy. Pediatr Radiol. 2005 Oct;35(10):1014-8.
• Bruegel M, Waldt S, Weirich G, Woertler K, Rummeny EJ. Multifocal epithelioid hemangioendothelioma of the phalanges of the hand. Skeletal Radiol. 2006 Oct;35(10):787-92.