Microscopic description:

Anastomosing vascular channels lined by plump hyperchromatic cells, suggestive of an atypical malignant vascular neoplasm

IHC: Positive ERG, CD31, Ki67 (25%); negative CDX2, SOX10, Ck20, PAX8, p63, TTF1, CAIX, AE1/AE3, CK7, Melan A

Discussion:

Rare vascular tumor with anastomosing vascular channels

Endothelial cells usually exhibit marked cytologic atypia, but it might be less pronounced in well differentiated ones

Irregularly shaped anastomosing vascular channels or sheet-like growth

Highly infiltrative architecture and poor demarcation

Multilayering of endothelial cells, nuclear atypia, increased mitoses, necrosis

Positive for vascular markers, such as CD31, CD34, ERG, VEGF and factor VIII, by immunohistochemistry; negative for HHV8, a Kaposi’s sarcoma marker

Primary renal angiosarcoma, also referred to as renal hemangiosarcoma, is an extremely rare neoplasm

Most cases occur in the sixth and seventh decades

Destructive lytic pattern on radiographs without a sclerotic margin

Angiosarcoma has a wide morphologic appearance, ranging from lesions that are cytologically bland and vasoformative, to solid sheets of highly pleomorphic cells without definitive vasoformation

Solid growth pattern often presents in poorly differentiated angiosarcoma

Tumor size, epithelioid component, high mitotic activity and margin status have been associated with adverse prognosis

References:

Omiyale AO, Carton J. Clinical and Pathologic Features of Primary Angiosarcoma of the Kidney. Curr Urol Rep. 2018 Jan 31;19(2):4. doi: 10.1007/s11934-018-0755-6. PMID: 29383452.

Lomasney LM, Martinez S, Demos TC, Harrelson JM. Multifocal vascular lesions of bone: imaging characteristics. Skeletal Radiol. 1996 Apr;25(3):255-61. doi: 10.1007/s002560050075. PMID: 8741063.

Lahat G, Dhuka AR, Hallevi H, Xiao L, Zou C, Smith KD, Phung TL, Pollock RE, Benjamin R, Hunt KK, Lazar AJ, Lev D. Angiosarcoma: clinical and molecular insights. Ann Surg. 2010 Jun;251(6):1098-106. doi: 10.1097/SLA.0b013e3181dbb75a. PMID: 20485141.

Naka N, Ohsawa M, Tomita Y, Kanno H, Uchida A, Myoui A, Aozasa K. Prognostic factors in angiosarcoma: a multivariate analysis of 55 cases. J Surg Oncol. 1996 Mar;61(3):170-6. doi: 10.1002/(SICI)1096-9098(199603)61:3<170::AID-JSO2>3.0.CO;2-8. PMID: 8637202.

Vorburger SA, Xing Y, Hunt KK, Lakin GE, Benjamin RS, Feig BW, Pisters PW, Ballo MT, Chen L, Trent J 3rd, Burgess M, Patel S, Pollock RE, Cormier JN. Angiosarcoma of the breast. Cancer. 2005 Dec 15;104(12):2682-8. doi: 10.1002/cncr.21531. PMID: 16288486.

CASE IMAGES