Wunderlich syndrome: cross-sectional imaging review.

Wunderlich syndrome (WS) is a rare condition characterized by acute onset of spontaneous, nontraumatic renal hemorrhage into the subcapsular and perirenal spaces. Wunderlich syndrome is classically characterized by the Lenk's triad: acute flank pain, flank mass, and hypovolemic shock. However, the clinical manifestations can be varied and nonspecific. A wide spectrum of neoplastic and nonneoplastic renal pathologies may result in WS. Renal neoplasms are the most common cause for WS, with angiomyolipoma being the most common benign neoplasm, whereas renal cell carcinoma is the most common malignant neoplasm. Other causative conditions of WS include vascular causes (vasculitis [polyarteritis nodosa being the most common cause], renal artery aneurysms, arteriovenous malformations and fistulas, and venous thrombosis), cystic renal diseases, renal infections, calculus disease, nephritis, and coagulation disorders. Cross-sectional imaging findings help in the detection of the subcapsular and/or perinephric hemorrhage and may identify underlying etiology. Renal angiography not only helps in diagnosis of the underlying cause in select cases but also allows control of active bleeding, which can avoid unnecessary emergent radical surgery.