Gouty sacroiliitis: A case report of an often-overlooked cause of inflammatory back pain.

Gout is a chronic disease caused by monosodium urate crystal deposition, typically affecting the big toe, midfoot, and ankle. As it rarely involves the sacroiliac joints, it could be easily misdiagnosed as spondylarthritis. Here, we report the case of a patient with a long history of gout with recurrent low back pain. Computed tomography of the sacroiliac joint suggested sacroiliac arthritis, puncture biopsy indicated gout granuloma, and polarized light microscopy confirmed monosodium urate crystal deposits.