Often misdiagnosed as spondyloarthritis? This article knows the clinical manifestations and treatment progress of SAPHO syndrome in the latest review

Many manifestations of SAPHO syndrome can be observed on routine x-rays, including hyperostophysis (thickening of the periosteum, cortex, and endosteal), sclerotic lesions, osteolysis, periosteal reactions, and attachment formation, but structural changes are insensitive
on radiographs.
Axial lesions such as vertebral keratosis and intervertebral discitis may be related to the spectrum of axial SpA disease, and these structural abnormalities are not recognized on x-rays early in the disease and need to be evaluated
by MRI.
Radiographic findings of peripheral arthritis include narrowing of the joint space, periarticular osteopenia, and bone erosion
.
Periostitis is a typical radiographic feature that may be indistinguishable
from osteomyelitis.

2.
Bone scan

Radionuclide bone scans may show increased
uptake at multiple sites affected.
With sternoclavicular joint involvement, the bullhead sign may be present on imaging, which is a
feature of SAPHO syndrome.
Bone scans can be used to examine multiple parts of bone and are a more targeted adjunct to the examination
.
However, given the risk of radiation exposure, bone scans should be used with caution
.

3.
CT

CT has a unique advantage
in showing spinal lesions and their extent.
A study of 69 patients with SAPHO syndrome showed that CT findings of the whole spine included thoracic spine lesions, cortical erosion, reactive osteosclerosis, and non-marginal ligamentous osteophytes
.
Differences from typical axial SpA include different forms of ligamentous osteophytes (non-marginal vs marginal) and paravertebral ligament ossification (anterior longitudinal and segmental vs posterior longitudinal and diffuse).

4.
MRI

MRI is a useful test for assessing prothoracic and axial skeletal involvement, detecting active inflammatory lesions, osteomyelitis (bone marrow edema), and providing soft-tissue data
early in the course of the disease.
The most common MRI findings of axial skeletal in SAPHO syndrome are anterior vertebral angle lesions
reflecting enthesitis.
MRI (T1 sequence) can detect structural damage such as erosions, bone hypertrophy, and joint rigidity
.
However, MRI also has disadvantages, in addition to its high cost and inaccessibility and relatively limited imaging range, patients with extensive lesions need to undergo multiple examinations
.

5.
Fluorodeoxyglucose (FDG) PET/CT

FDG PET/CT has been shown to be effective in differentiating between active and inactive lesions in patients with SAPHO syndrome and helping to rule out metastatic disease
in refractory cases.
Currently used only in complex cases
.

6.
Ultrasound

Musculoskeletal ultrasound is a diagnostic tool
for the evaluation of synovitis, enthesitis, peripheral disease, and early anterior chest wall inflammation.
Synovitis
with energy Doppler signal can be detected in the sternoclavicular and peripheral joints in patients with SAPHO syndrome compared to the control group.

How is SAPHO syndrome treated?

The main treatment goals of SAPHO syndrome include relieving joint and skin symptoms, preventing bone damage, and improving quality of life
.
Due to the lack of clinical trials for this rare disease, existing treatments lack evidence-based evidence, and treatment options are mostly based on case reports, retrospective studies, and several open-label trials, often off-label medications
.
NSAIDs are considered first-line therapy, but efficacy may be limited
.
Second-line therapies include antibiotics, bisphosphonates, and disease-modifying antirheumatic drugs (DMARDs).

Methotrexate is the most commonly used oral DMARD, but its efficacy in osteomyelitis is unclear
.