Differential features of SAPHO.
| SAPHO syndrome | Synovitis, acne, pustulosis, hyperostosis, osteitis. Not all patients have all features and some may have only one |
| Chronic recurrent multifocal osteomyelitis | In pediatrics often diagnosed as a unique entity, in adults classed as part of the SAPHO spectrum |
| Pustulotic arthro-osteitis | Now considered synonymous with SAPHO |
| PAPA (pyogenic arthritis, pyoderma gangrenosum, acne) syndrome | Autosomal dominant disease. Causes non-axial sterile pyogenic arthritis followed by joint ankylosis |
| Psoriatic arthritis | Osteitis mainly adjacent to entheseal sites. Some experts believe SAPHO to be a variant of psoriatic arthritis |
| Enteropathic arthritis | Osteitis can occur in a similar pattern to psoriatic arthritis. Pyoderma gangrenosum and erythema nodosum can occur |