Enteropathic SAPHO Syndrome in Ulcerative Colitis Responsive to Bisphosphonates.

SAPHO syndrome, a rare inflammatory disorder of bone, joints, and skin, is named based on the presence of synovitis, acne, pustulosis, hyperostosis, and osteitis. The hallmark of SAPHO syndrome includes osteoarticular and dermatologic manifestations, however, rarer associations with inflammatory bowel disease (particularly Crohn's disease) have been documented. The literature on the relationship between SAPHO syndrome and inflammatory bowel disease (IBD), especially ulcerative colitis (UC), remains limited. We report an unusual case of SAPHO syndrome in a patient with UC. Chest x-ray and MRI showed enlargement of the right first rib and adjacent sternum. Bone scintigraphy revealed hyperostosis and ankylosis of the costochondral junction, and bone biopsy revealed reactive bone and costal cartilage without findings of infection or malignancy. Complete resolution of symptoms was achieved 4 months after starting zoledronic acid without significant adverse events. The diagnosis of SAPHO syndrome in IBD patients is rare, even more so in UC patients, likely attributable to underdiagnosis given the clinical heterogeneity of SAPHO syndrome and overlap with the extra-intestinal manifestation of IBD. Our treatment approach provides critical data to the underreported literature on diagnosis and managing SAPHO syndrome in UC.