A rare hemangioma arising from synovium lining surfaces. The disease is Monarch Disease Ontology id MONDO_0004519 (synovial angioma). Also known as: angioma of synovium, angioma of the synovium, hemangioma of layer of synovial tissue, hemangioma of synovium, hemangioma of the synovium, layer of synovial tissue hemangioma, synovial hemangioma.