SAPHO is an acronym that is manifested by a combined occurrence of
- S: synovitis
- A: acne
- P: pustulosis
- H: hyperostosis
- O: osteitis
It is an inflammatory condition with predominant non-infective osteoarticular involvement.
It is seen in all ages,
classically tends to present in young to middle aged adults.
There is slight female predisposition.
The appearances of the osteitis can be very aggressive mimicking infection or neoplasm.
Chronic recurrent multifocal osteomyelitis (CRMO) is the association of multifocal osteitis with pustulosis palmaris et plantaris seen in childhood with predominant affection of the long bones.
There are different stages at which the disease can present with episodes of remission and recurrence.
The patients can present with pain,
and limited movement at the site of involvement due to active inflammation.
The osteoarticular manifestations associated with SAPHO and skin changes may not coexist.
There is a latency period of up to 38 years,
so the absence of the skin changes should not exclude the diagnosis of SAPHO.
Radiological manifestation of the disease:
- In the early disease stages,
the lesions are osteodestructive .
- The osteoarticular manifestations include synovitis,
osteitis and arthropathy.
- Arthritis has been frequently reported during the stages of SAPHO.
It is more commonly seen in the synovial joints (such as the sternoclavicular joint),
the costochondral and symphyseal joints e.g manubriosternal and pubic joints.
- The disease tends to be osteoproliferative at later stages with evidence of hyperstosis and increased sclerosis of the bone due to chronic inflammatory reactions.
This is associated with chronic endosteal and periosteal reaction causing cortical thickening and narrowing of the medullary canal.
- Radiographs are mostly normal in the first few months of the disease in 80% of the cases.
MRI is the modality of choice to demonstrate early soft tissue and marrow oedema.
It is also used for follow up and assessment of the disease response to treatment.
Whole-body bone scintigraphy is very useful to demonstrate additional skeletal lesions.
There is increased use of the 18FDG-PET/CT in detecting and localizing active inflammatory lesions in SAPHO.
It helps to differentiate between active and inactive SAPHO lesions especially when these appear “hot” on bone scintigraphy.
Sites of Involvement:
This depends on the age at first presentation.
The commonest sites affected in children and adolescents are long bone metaphyses followed by clavicles.
there is predilection for the anterior chest wall with the sterno-costo-clavicular joint being most commonly affected by the disease followed by the spine and sacroiliac joints.
The SAPHO can affect multiple different skeletal areas as seen in 65% of the patients.
It can be very challenging due to variability of clinical presentation and broad spectrum of imaging appearances.
The main feature of SAPHO is aseptic osteitis.
The surrounding soft tissue thickening and inflammation around the affected bones and joints can be very extensive and misinterpreted as a malignancy.
In many cases biopsy has to be performed to exclude other pathology.
and Paget’s disease.
lymphoma and metastases.
Usually symptomatic with nonsteroidal anti-inflammatory drugs being most commonly prescribed.
bisphosphonates and TNF alpha antagonists have also been used to control the disease.