The SAPHO syndrome is an acronym that refers to a rare syndrome that is manifested by a combined occurrence of ²:

• S: synovitis

• A: acne

• P: pustulosis

• H: hyperostosis

• O: osteitis

Epidemiology

SAPHO classically tends to present in young to middle-aged adults. Presentation in the paediatric population is not uncommon. There may be slightly higher female predilection ⁸.

Pathology

SAPHO and related conditions have three stages of progression, which are described as:

1. costoclavicular ligament ossification

2. arthropathy of the sternoclavicular joint, osteitis of the medial end of the clavicle, first rib and sternum as well as hypertrophy of the costal cartilages

3. osteitis, hyperostosis and hypertrophy of the medial ends of the clavicles, sternum and upper ribs and ultimately ankylosis

Aetiology

Many causes have been suggested with infectious aetiology considerably favoured. Propionibacterium acnes, an anaerobic saprophyte found in human skin, has been isolated from the biopsy specimens of bone and synovium ⁸.

Serology

• HLA-B27: may be positive in around 30% of patients ⁸

Radiographic features

Plain radiograph

Plain radiograph is non-specific, but SAPHO syndrome can be suspected if present with the other clinical findings:

• sternoclavicular joint: most common location of involvement, with osteitis and hyperostosis

• sacroiliitis

• osteosclerosis of vertebral bodies

• long bones: metaphyseal osteosclerosis and osteolysis ⁵

Nuclear medicine

Increased uptake at bone scan centred on both sternocostoclavicular joints in the characteristic "bull's head" configuration. 

Treatment and prognosis

Tends to be benign although patients may have recurrent bouts of attacks. Pamidronate therapy has been successfully trialed for symptom relief (especially in the paediatric population) ⁶.

Differential diagnosis

For bony features in children consider

• chronic recurrent multifocal osteomyelitis (CRMO)  

History and etymology

Chamot et al. initially described it in 1987 ³.