Epitheloid hemangioendothelioma: Year of the Zebra 2025

Epithelioid hemangioendothelioma, or EHE for short, is a very rare type of tumor that originates from endothelial cells in the inner lining of blood vessels. When these cells become abnormal, they change their shape under the microscope. Instead of staying thin and flat, they become rounder and fuller, almost resembling the epithelial cells that line organs, hence the name epithelioid.

What makes EHE unique is that it doesn’t behave like a classic benign tumor, but it also doesn’t show the rapid growth or aggressive spread of high-grade cancers. Instead, it falls somewhere in between, meaning some people have slow, stable disease for years, while others can experience growth or metastases over time.

Now, since endothelial cells can be found everywhere where there's blood flow, EHE can develop in almost every organ, including the liver, lungs, bones, and soft tissues. Typically, it causes few symptoms, and when it does, they tend to be quite subtle.

For example, in the liver, it can cause discomfort in the upper abdomen, fullness after meals, or mild nausea;
whereas in the lungs, it can lead to persistent dry cough, slight shortness of breath, or chest tightness. Localized pain and vascular congestion are common, and generalized symptoms such as fever or weight loss can occur in association with tumor spread.

Less commonly, EHE can develop in bones, especially weight-bearing bones like the femur, tibia, pelvis, or spine. People often notice persistent, localized pain, similar to the soreness you might feel after accidentally bumping into furniture. The bone may feel tender or swollen, and in rare situations, the affected bone might become weak enough that a minor fall or twist causes a fracture.

Although not as common, EHE can also present as a slowly enlarging lump in muscle or soft tissues, which can be painless or cause a dull ache.

As for diagnosis, EHE is often discovered incidentally on an ultrasound or a CT scan done for another reason. Typically, it appears as small, multiple nodules scattered throughout the affected tissue. Its radiologic characteristics and slow-growing pattern help differentiate it from more aggressive malignancies.