Sacroiliitis or insufficiency fracture?

Sacral stress fracture and sacroiliitis are two conditions that present with pain. Sacral stress fractures are a rare cause of lumbar and hip pain. Sacral insufficiency fractures are a type of sacral stress fractures. Sacroiliitis represents inflammation of the sacroiliac joints. Coexistence of sacroiliitis and sacral insufficiency fracture (SIF) has not been reported before. Case 1: A 39-year-old woman reporting inflammatory back pain. Imaging revealed bilateral chronic sacroiliitis and bilateral SIF. Case 2: A 31-year-old woman presenting with left hip and inguinal pain. Imaging revealed left sacroiliitis and ipsilateral SIF. Calcium and vitamin D supplementation together with nonsteroidal anti-inflammatory drug (NSAID) treatment were given. Sulfasalazine was added to the treatment of the second patient who developed peripheral arthritis during follow-ups. Early diagnosis is best made with magnetic resonance imaging (MRI) since roentgenograms may be negative initially. Furthermore, MRI findings of both entities share common features leading to a diagnostic dilemma. Interpretation of radiological findings assisted by detailed history and clinical findings is crucial for diagnosis and treatment.