Microscopic description:

Wide range of morphologic appearances, ranging from well-formed anastomosing vascular channels to solid sheets of high-grade epithelioid or spindle cells

Vasoformative areas consist of ramifying channels composed of highly atypical endothelial cells forming intraluminal buds and/or papillae

IHC:

Positive for CD34, CD31, ERG, FLI1 and occasionally podoplanin

May sometimes co-express epithelial antigens such as low molecular-weight cytokeratins, particularly in epithelioid angiosarcomas

Negative for high molecular-weight cytokeratins and HHV8 (latter positive in Kaposi’s)

Discussion:

High-grade malignant lesion of vascular origin. Most cases occur in the sun-exposed skin or superficial soft-tissue of individuals with chronic lymphedema

Association with radiation exposure (ie, adjuvant RT), Thorotrast contrast media, industrial vinyl chloride and implanted foreign material

Upregulation of receptor tyrosine kinases, including FLT1, as well as transcriptional regulators HIF-1/2α

MYC amplification is seen in radiation-induced angiosarcoma

Linked to Klippel-Trenaunay and Maffucci syndromes

Primary renal angiosarcoma is extremely rare, with approximately 64 cases in literature

Primarily affects elderly males

Most common presentation is flank pain

May rupture resulting in retroperitoneal hematoma

Highly aggressive malignancy; most are metastatic at the time of diagnosis

Prognosis is almost uniformly fatal

References:

Zhang H, et al. Primary angiosarcoma of the kidney: case analysis and literature review. Int J Clin Exp Pathol. 2014; 7(7): 3555-62

Omiyale AO, et al. Clinical and Pathologic Features of Primary Angiosarcoma of the Kidney. Curr Urol Rep. 2018; 19(2): 4

Fletcher CDM, Bridge JA, Hogendoorn PCW, Mertens F. (2013) WHO Classification of Tumours of Soft Tissue and Bone. (4th Ed.) Geneva: WHO Press

CASE IMAGES