Objective: Angiosarcomas and hemangioendotheliomas are rare malignant vascular neoplasms (MVTs). Here, we reviewed the clinicomorphological characteristics of 27 MVTs with the implementation of two novel immunohistochemical markers: GLUT1, and FKBP12.

Material and Method: MVTs, except for Kaposi's sarcoma, were retrieved from the archive and reviewed. Tumor size, the presence of hemorrhage and necrosis, growth pattern, cellularity, cellular characteristics and mitotic activity were recorded as morphological variables. Immunohistochemically, CD34, CD31, GLUT1, FKBP12, mdm2, p53, c-kit, and CD99 were applied. Clinical information was gathered from hospital records and computer-based patient data systems.

Results: The median age was 53 years (range 16-77). Extremities (37%) were the most common primary site followed by the head and neck. Five of 16 (31%) low grade and 7 of 11 (64%) high grade tumors were metastasized to varying organs, mainly the liver and lungs. The median survival was 49 months. Ninety percent of high grade tumors were larger than 3 cm. Hemorrhage and necrosis were seen in 85% and 41% of cases, respectively. Nuclear pleomorphism, cellularity and mitotic activity were higher in high grade tumors than in low grade ones (p<0.0001). While 68% of the cases expressed CD34, 81% of them were positive with CD31. All cases except one low grade tumor were strongly and diffusely stained with FKBP12. Significant GLUT1 expression was observed in 23% of cases, especially in areas showing epithelioid morphology. Either mdm2 or p53 was positive in over one third of the tumors.

Conclusion: The studied markers were not able to distinguish between low and high grade MVTs. FKBP12 may take a role in the diagnostic panel of MVTs. GLUT1 expression, previously proposed for the diagnosis of infantile hemangioma, should be assessed carefully since almost one quarter of MVTs were also GLUT1 positive.