Retroperitoneal hemangioma

Retroperitoneal hemangiomas are almost always of the cavernous hemangioma subtype .
Clinical presentation
They tend to be asymptomatic, especially in the early stages of their development, but when present, symptoms are non-specific and due to mass effect on the adjacent anatomic structures.
Radiographic features
CT & MRI
On CT and MRI, hemangiomas are generally well defined with round or lobular margins, and with low attenuation, low signal intensity on T1-weighted imaging, and high signal intensity on both T2-weighted imaging and heavily T2-weighted imaging relative to skeletal muscle.
Calcified phleboliths, when visualized, have very low signal intensity on both T1-weighted imaging and T2-weighted imaging, are better visualized on CT, and are strongly suggestive of the diagnosis.
Non-parenchymal hemangiomas in the abdomen usually demonstrate progressive enhancement .
Treatment and prognosis
Treatment is conservative, with surgical removal reserved for symptomatic lesions or to establish a tissue diagnosis .