Clinical Presentation

A 37-year-old man presents to the clinic with a history of pelvic pain.

Further Work-up

(A) Infused computed tomographic (CT) scan shows enhancing mass abutting the bladder (arrows). The calcification is a phlebolith. (B) Higher cut shows right perirectal serpiginous structures (arrowhead). (C) Early phase pelvic angiogram shows the nidus (arrowhead) of a vascular malformation supplied by hypogastric (arrow) branches. (D) Selected hypogastric arteriogram shows large draining veins (arrow). (E) Multiple branches have been coiled and treated with N-butyl cyanoacrylate adhesive.

Differential Diagnosis

• Arteriovenous (a-v) malformation: The congenital type of pelvic a-v shunt is indicated by the dense nidus and enlarged, early draining veins.
  
• Arteriovenous fistula: More commonly an acquired shunt with one or a few a-v communications rather than a nidus.