A pain in the bottom

Case history

An 82 year old woman presented with a two week history of sudden onset pain “right inside my bottom.” The pain was most severe on standing or sitting, and she had become bedridden. The onset of pain had been spontaneous with no history of trauma. Her general health was reported to be good. She was receiving treatment for osteoporosis with a bisphosphonate and calcium and vitamin D supplements, having previously fractured the neck of her left femur and left distal ulnar. When she was asked to stand, she became unable to move and screamed out in pain. There was tenderness over the sacral area. Rectal examination was normal. A radiograph of the pelvis and lower spine showed osteopenia and degenerative changes at L5-S1. Full blood count, renal function, and calcium were normal. Alkaline phosphatase was mildly elevated at 383 IU/l.

Questions

• 1 What is the most likely diagnosis?

• 2 What is the most common underlying pathology in this condition?

• 3 Which imaging technique is considered to be the …