Epithelioid hemangioendothelioma of the lung (IVBAT) - clinicopathological and immunohistochemical analysis of 11 cases

Epithelioid hemangioendothelioma (EHE) of the lungs (syn.: intravascular bronchioloalveolar tumor/IVBAT) is a neoplasm with a vascular line of differentiation. This study provides a clinicopathological analysis of 11 cases of this tumor. There were 7 female and 4 male patients. Patients' age ranged from 33 to 83 years (mean: 49.8, median: 48 years) showing 2 peaks (third/fourth and sixth/eighth decades). The typical radiological appearance revealed multiple bilateral lung nodules from 0.5 to 2 cm. In 2 cases, a striking perivascular and intravascular growth pattern associated to pulmonary veins was evident. All tumors were characterized by epithelioid tumor cells with nests, cords and strands embedded in a sclerosing, hyaline matrix with alveolar, bronchiolar and vascular extension. Necrosis was identified in 8 tumors and ossification in 2 tumors. The mitotic index was below one mitosis in 10 HPF. By immunohistochemistry, all tumors were positive for CD 31, CD 34, and vimentin, 60% positive for factor VIII, and negative for pancytokeratin and calretinin. Follow-up was available for 8 patients with a range of 6 to 105 months (mean: 51.5 months, median: 52 months): 3 patients died (2 certainly from their tumors), 4 are alive disease-free, and one is alive with metastases. EHE of the lungs (IVBAT) represents an intermediate-grade, malignant, mesenchymal neoplasm with a characteristic histological appearance and immunohistochemical profile.