Angiosarcoma is a malignant tumor arising from the endothelial cells of blood vessels. Per Orphanet and GARD (NIH), the condition is classified as very rare, with an estimated prevalence of fewer than 1 in 1,000,000. Microscopically, the tumor is characterized by anastomosing and branching vascular channels lined by spindle or epithelioid cells with hyperchromatic nuclei. The condition most frequently arises in the skin and breast. Long-standing lymphedema is documented as a risk factor. Onset category data are not documented in this packet.

Specific phenotypic features are not enumerated in this packet. Angiosarcoma is documented across 19 anatomical subtypes including liver angiosarcoma, bone angiosarcoma, breast angiosarcoma, scalp angiosarcoma, skin angiosarcoma, and pediatric angiosarcoma, each associated with site-specific clinical presentations.

Genetic associations are not catalogued in this packet. No inheritance pattern is documented, consistent with an acquired malignancy. The packet definition identifies long-standing lymphedema as a documented risk factor for angiosarcoma development.

Diagnostic criteria and biomarkers are not catalogued in this packet beyond pathological description. Microscopically, characteristic features include anastomosing vascular channels lined by atypical spindle or epithelioid endothelial cells displaying hyperchromatic nuclei.

No FDA-approved treatments are documented for angiosarcoma in this packet. Two orphan drug designations are recorded — Oraxol (Health Hope Pharma) and a PEG-b-PLA micellar formulation (Co-D Therapeutics) — but orphan designation does not constitute FDA marketing approval.

Natural history and prognosis data are not populated in this packet.

ClinicalTrials.gov lists 26 active trials. Registered studies include a Phase 2 trial of intratumoral vusolimogene oderparepvec combined with pembrolizumab (NCT06898970), a Phase 2 pilot study of ivonescimab in advanced cutaneous angiosarcoma (NCT07655570, MD Anderson Cancer Center), a Phase 2 investigation of pembrolizumab plus lenvatinib in unresectable cutaneous angiosarcoma (NCT06673628, National Cancer Center Japan), and a Phase 2 study of nivolumab and ipilimumab in rare tumors (NCT02834013, NCI). The research landscape includes 245 classified publications, with case reports as the dominant publication type.