Do you know? Open the door┋ SAPHO syndrome: a rare inflammatory disease of bones, joints and skin

Author: Zhang Chenxi, resident physician in the Department of Rheumatology and Immunology, the First Affiliated Hospital of Xinjiang Medical University.

Review expert: Luo Li, chairman of the Clinical Immunology Branch of the Xinjiang Immunology Society; vice president of the Xinjiang Uygur Autonomous Region Immunology Society; director, professor and chief physician of the Department of Rheumatology and Immunology, the First Affiliated Hospital of Xinjiang Medical University.

SAPHO syndrome is a rare, chronic inflammatory disease that involves lesions in the skin, bones, and joints. Although its name may not be well known, understanding its symptoms, diagnosis, and treatment is crucial for early detection and treatment. This article will explore various aspects of SAPHO syndrome in depth to help everyone better understand this disease.

What is SAPHO syndrome? SAPHO syndrome is an acronym composed of five English words, namely synovitis, acne, pustulosis, hyperostosis and osteomyelitis. It is a chronic disease that mainly affects the skin, bones and joints, and its clinical manifestations are diverse and highly heterogeneous.

Historical background

SAPHO syndrome was first reported by Japanese doctor Sasaki in 1967, who described a case with sterno-clavicular arthritis and palmoplantar pustulosis. Subsequently, French doctor Charot proposed in 1987 that patients with similar features should be classified as SAPHO syndrome and the disease was officially named.

Clinical manifestations

1. Skin manifestations

Patients with SAPHO syndrome often present with skin lesions, including acneiform dermatosis and neutrophilic dermatosis. Common skin manifestations include:

Palmoplantar pustulosis (PPP), which presents as pustules on the palms and soles. Severe acne, such as acne conglobata, acne fulminans, or hidradenitis suppurativa. These skin lesions often coexist with bone and joint lesions and are important clues to the diagnosis of SAPHO syndrome.

2. Bone and joint manifestations

Bone and joint lesions are one of the core features of SAPHO syndrome, mainly including:

Bone hypertrophy and sclerosis, especially in the anterior chest wall (sternoclavicular joint and sternocostal joint), are the hallmarks of SAPHO syndrome. Sacroiliitis: About 50% of patients will have unilateral sacroiliitis, which is manifested by erosion, extensive sclerosis and bone hypertrophy adjacent to the iliac side of the joint. Spinal lesions, mainly involving the thoracic and lumbar segments, may have vertebral angle lesions and spondylitis. Peripheral synovitis, which occurs in about 30% of patients, is manifested by joint pain, swelling and tenderness, commonly in the hip, knee and ankle joints.

Imaging examinations and their characteristics

Imaging examinations play a key role in the diagnosis of SAPHO syndrome. Common imaging examination methods include:

1. X-ray Conventional X-ray examinations can observe features such as bone hypertrophy, sclerotic lesions, osteolysis, periosteal reaction, and attachment formation. However, X-rays are not sensitive enough to detect early lesions.

2. Bone scan Radionuclide bone scan can show increased uptake in multiple affected areas. When the sternoclavicular joint is involved, a bull head sign may appear on the imaging, which is one of the characteristics of SAPHO syndrome.

3. CT and MRI CT has unique advantages in showing spinal lesions and their extent. MRI can more clearly show soft tissue lesions, such as synovitis and osteomyelitis, and is more sensitive in diagnosing early lesions.

Diagnosis and differential diagnosis

The diagnosis of SAPHO syndrome is mainly based on clinical manifestations and imaging examinations. The commonly used diagnostic criteria are the Kahn criteria, which include:

Chronic recurrent multifocal sterile, axial osteomyelitis with or without skin disease. Acute, subacute, or chronic arthritis associated with palmoplantar pustulosis, pustular psoriasis, or severe acne. Any sterile osteitis associated with palmoplantar pustulosis, pustular psoriasis, or severe acne. In the diagnostic process, it is necessary to differentiate from psoriatic arthritis, ankylosing spondylitis, Reiter's syndrome, and sclerosing osteomyelitis.

Pathogenesis

The pathogenesis of SAPHO syndrome is not yet fully understood, but studies have shown that it may be related to Propionibacterium acnes infection and the HLA-B27 gene. Propionibacterium acnes can be found in joint tissues of about half of patients through pathological biopsy, and about 1/3 of patients are HLA-B27 positive.

treat

Since the cause of SAPHO syndrome is unknown, current treatment is mainly symptomatic treatment, with the goal of relieving symptoms and improving the patient's quality of life. Commonly used treatments include:

Nonsteroidal drug treatment

Nonsteroidal drugs (such as NSAIDs) are the first choice for the treatment of SAPHO syndrome and can effectively relieve pain and inflammation.

For patients with severe inflammatory reactions and ineffective non-steroidal drugs, small to medium doses of corticosteroids can be used for a short period of time.

Methotrexate and sulfasalazine For patients with obvious peripheral joint synovitis or obvious skin lesions, methotrexate can be tried. Sulfasalazine can be tried in patients with inflammatory bowel disease.

Bisphosphonates: A new generation of bisphosphonates, pamidronate, has been shown to be effective in treating SAPHO syndrome. Generally, pamidronate 600 mg/d is taken orally for about 6 months to effectively relieve symptoms.

Prognosis

SAPHO syndrome usually has a good prognosis, slow progression, and no obvious disability or serious complications. However, patients with a long course of the disease may experience problems such as fusion of the sternocostal clavicle junction and bone hypertrophy compressing adjacent neurovascular structures, which require timely intervention.

Prevention and care

Because the cause of SAPHO syndrome is unknown, preventive measures are limited. Early diagnosis and treatment are the key to improving the quality of life of patients. In daily life, patients should pay attention to keeping their skin clean and avoiding infection, while regularly undergoing imaging examinations to monitor changes in the condition.

Conclusion

SAPHO syndrome is a rare chronic inflammatory disease with diverse and highly heterogeneous clinical manifestations. Although its etiology is unknown, early diagnosis and appropriate treatment can effectively control symptoms and improve the quality of life of patients. Improving awareness of SAPHO syndrome will help early detection and treatment, and reduce the occurrence of misdiagnosis and missed diagnosis.

Although SAPHO syndrome is rare, it should not be ignored. If the above symptoms occur, you need to see a rheumatologist in time. I hope that through the introduction of this article, everyone can better understand this disease and provide better help and support for patients.