Hemangioma is a rare mesenchymal benign tumor of the bladder, which accounts for 0.6 % of all bladder tumors. The most common symptom is gross, painless hematuria.

CT scans have been reported to detect diffuse thickening of the bladder wall with multiple loci of calcification or extravesical extension. CT scans were also useful in revealing a hypervascular mass of the bladder in the present case.

MR imaging has been reported to be valuable in the diagnosis of soft tissue hemangiomas. Hemangiomas demonstrate relatively low signal intensity on T1-weighted images and an intense signal on T2-weighted images. These MR images reflect the content of the lesions, that is, stagnant or slowly flowing blood. MR imaging is useful in defining the extent, size, and location of the tumor in three dimensions. MR imaging has been reported to be superior to CT and US in demonstrating the extent of hemangioma.

Hemangiopericytoma (HPC) is one of the rarest renal tumors. HPC is an unusual perivascular tumor, classified as a soft tissue vascular tumor featuring the uncontrolled proliferation of pericytes, which are cells spiralling around capillaries.

No characteristic signs of renal HPC have been described on ultrasonography, CT, or MRI that might aid in the differential diagnosis. These studies usually depict a large mass, which may grow insidiously to a diameter of 25 cm, but with no pathognomonic features. CT may show a large heterogeneous mass, with calcifications and areas of necrosis. These tumors may have a characteristic pattern in the early arterial phase of angiography, with displacement of the main arteries, presence of large vessels encircling the tumor, and a well-demarcated tumor stain.

The most common cause of renal hemorrhage is trauma, either blunt or penetrating. Extracorporeal shock wave lithotripsy for nephrolithiasis is not infrequently associated with parenchymal and perinephric hemorrhage. Spontaneous renal hemorrhage may be caused by anticoagulation, blood dyscrasias, renal infarction, polyarteritis nodosa, renal aneurysms and arteriovenous malformations, renal cell carcinoma (RCC), acute myeloid leukemia, renal abscess, renal vein thrombosis, and rupture of hemorrhagic solitary cysts or of hemorrhagic cysts in renal cystic disease. Some cases are idiopathic. RCC is probably the most common cause of spontaneous subcapsular and perinephric hemorrhage.

CT is the most valuable examination in the evaluation of patients with suspected acute renal hemorrhage because it accurately diagnoses the presence and location of such hemorrhage and often shows the underlying cause. Renal hemorrhage may be suburothelial, intraparenchymal, subcapsular, perinephric, or pararenal in location or may involve the renal sinus. Recent renal hemorrhage is characterized by high-attenuation blood, which is best shown by unenhanced CT scans. Postcontrast scans should also be obtained to facilitate identification of disorders such as small neoplasms causing spontaneous renal hemorrhage. Suburothelial hemorrhage is characterized on CT by thickening of the wall of the renal pelvis and upper ureter by blood that has a high-attenuation value on unenhanced scans. Spontaneous hemorrhage into the renal sinus is characterized by a high-density blood collection in the renal sinus with displacement of the renal pelvis. On an unenhanced CT scan, a recent subcapsular hematoma is characterized by a mass with a higher attenuation value than that of adjacent renal parenchyma. Pressure on the underlying renal parenchyma characteristically causes flattening of the kidney, elevation of the renal capsule, and medial displacement of the collecting system. However, although subcapsular hematomas are confined to the kidney by the renal capsule, perinephric hematomas often extend caudally below the kidney into the cone of renal fascia.