A symptomatic pelvic digit with surgical and pathological correlation

Pelvic digits (also known as pelvic fingers or pelvic ribs) are rare supernumerary benign bony lesions. Most of them are asymptomatic but, when symptomatic, they can pose a diagnostic challenge. We hereby present a case of a pelvic digit responsible for an organic erectile dysfunction and a disabling pain in the sitting position. Pelvic radiographs showed a 2-cm ossified cannulated structure emerging from the right ischiopubic ramus, extending down into the right perineal soft tissues. MRI revealed a well-defined cortico-medullary digit with typical bone signal, developing near the hypertrophied root of the right corpus cavernosum and the insertion of the right adductor magnus muscle. The CT scan confirmed a pelvic digit with a pseudarthrotic single joint on the ischium. After a thorough 2-step surgical resection, pathologists confirmed the diagnosis. This particular radiologic challenge was to differentiate a pelvic digit from osteochondroma, avulsion-fracture sequelae, ligamentous calcification and myositis ossificans.