16. Do You Recognize this Syndrome?

Abstract

Background: 53 year old Caucasian female presented to rheumatology with a 4-year history of progressive enlargement of her left clavicle with intermittent pain. She denied any proceeding trauma. There were no associated features of spondyloarthritis or systemic upset. Past medical history included acne. Methods: On examination the left clavicle was prominent and nontender. Systems and joint examination were unremarkable. She had palmoplantar pustulosis. Chest X-ray showed proximal expansion and sclerosis of the left clavicle. Remarkable bloods: pls 524, neuts 6.9, CRP 30 and ESR 56. Bone scan showed intense uptake in the left clavicle with no other suspicious masses. A diagnosis of SAPHO was made on the clinical presentation of palmoplantar pustulosis, acne and hyperostosis of the left clavicle. Treatment with 15mg of MTX weekly was started. Results: Despite treatment for a year and escalation to 20mg of MTX there was no improvement in the inflammatory markers or clinically. Repeat CT scan at 1 year showed worsening of sclerosis in the left clavicle. Azithromycin 250mg daily was added. Despite 3 months of treatment there was no improvement. Her medications were stopped and she had a bone biopsy with histology showing chronic sclerosing osteomyelitis. Bone cultures grew Propionibacterium acnes in 2/3 samples, sensitive to amoxicillin (1g tds for 3/12). Her inflammatory markers improved after 2 weeks of treatment and after 3 months she no longer experienced pain and her inflammatory markers had normalized. Conclusion: SAPHO is beginning to be recognized as a reactive infectious osteitis with genetic, immunological and bacterial mechanisms being implicated in disease pathogenesis. P. acnes may have an important role in the development of SAPHO and may therefore justify antibiotic treatment over more commonly used antirheumatic drugs. Randomized control studies are required to confirm the effects and duration of treatment with antibiotics in SAPHO.