This transcript provides an overview of Epithelioid Hemangioendothelioma (EHE), a rare vascular tumor. The presentation distinguishes between aggressive organ-based disease (lung and liver, associated with high morbidity and mortality, sometimes requiring transplant) and typically more indolent skin/soft tissue presentations, while emphasizing that metastasis from internal sites to the skin must be ruled out. Microscopically, EHE is characterized by epithelioid cells arranged in cords and nests within a sclerotic background, often exhibiting "blister cells" (cytoplasmic vacuoles representing abortive vascular lumen formation). Diagnosis is complicated because EHE may express cytokeratin, mimicking carcinoma, and its vacuolated cells can resemble other vascular tumors. The definitive diagnostic tools are vascular markers and molecular testing, which identifies the characteristic WWTR1-CAMTA1 translocation in the majority of cases.
Epithelioid Hemangioendothelioma (EHE): Clinical and Pathological Features
0:03 High Morbidity Disease: Epithelioid Hemangioendothelioma (EHE) commonly affects the lung and liver, resulting in high morbidity and mortality (up to 50% mortality). Many patients require organ transplants.
0:21 Skin vs. Organ EHE: A minority of cases (around 10%) occur in the skin or soft tissue. These tend to be more indolent but can still metastasize and be fatal.
0:40 Metastasis Warning: Organ-based EHE can metastasize to the skin, mimicking a primary tumor. Clinicians must scan patients to rule out underlying internal disease.
1:19 Microscopic Appearance: EHE appears as a dermal or subcutaneous nodule. Classic features include epithelioid cells arranged in cords, chains, or small nests.
1:35 Diagnostic Blister Cells: The cells exhibit vacuoles in their cytoplasm, referred to as "blister cells." These are abortive vascular lumens, sometimes containing red cell fragments, which reflect the tumor cells' attempt to form vascular channels.
2:16 Important Caveat: While characteristic, vacuoles are not exclusive to EHE and can be found in other plump epithelioid vascular tumors.
2:36 Differentiation from Angiosarcoma: EHE usually lacks well-formed, infiltrated vascular channels, which helps distinguish it from angiosarcoma.
3:11 Mimicking Carcinoma: EHE may express cytokeratin, posing a diagnostic trap by making it appear like metastatic carcinoma (e.g., breast cancer). Vascular markers are necessary to solve this differential diagnosis.
3:35 Molecular Signature: The majority of EHE cases are characterized by the WWTR1-CAMTA1 translocation. A small subset shows the YAP-TFE3 translocation. These translocations can be tested via FISH (fluorescence in situ hybridization) in difficult cases, which is crucial for determining appropriate patient treatment.