Characterization of the immune response in the synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome

SAPHO syndrome: current clinical, diagnostic and treatment approaches

This review provides an overview of SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis), a rare autoinflammatory disease that primarily affects bones, skin, and joints. We conducted a search on Medline/PubMed using keywords such as SAPHO syndrome, chronic recurrent multifocal osteitis/osteomyelitis, and related terms. SAPHO syndrome is rare, with a reported frequency of 1 in 10,000 in the Caucasian population. However, the actual incidence of SAPHO syndrome is unknown, and the incidence of the disease is likely higher. The pathogenesis of SAPHO syndrome remains incompletely understood. Current evidence suggests that SAPHO results from a complex interplay between immune dysregulation, genetic susceptibility, and environmental factors. It's not clear if SAPHO syndrome is an autoimmune disease or an autoinflammatory disease, but current evidence suggests that it's more likely an autoinflammatory disease because of things like neutrophil hyperactivity, fewer natural killer (NK) cells, high levels of interleukin (IL)-1, and a good response to treatments that block IL-1. Osteo-articular (OA) involvement is a key clinical feature of SAPHO. It affects the anterior chest wall, axial skeleton, peripheral joints, mandible, long bones of the extremities, and pelvis. Dermatological involvement is a common target in SAPHO, with lesions observed in 60-90% of cases. Common skin lesions include psoriasis and acne, with hidradenitis suppurativa and neutrophilic dermatoses being less commonly seen. Other clinical findings include constitutional symptoms caused by systemic inflammation, such as fever, weight loss, and fatigue. There is no specific laboratory finding for SAPHO syndrome. However, during active disease, there may be an increase in positive acute phase markers, such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complement levels, mild leukocytosis, and thrombocytosis. Diagnosis is crucial for SAPHO syndrome, which lacks a specific diagnostic finding and is often underrecognized. A comprehensive evaluation of a patient's medical history and physical examination is crucial. Treatment options include non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, conventional and synthetic disease-modifying agents (cDMARDs and sDMARDs), biological therapies, bisphosphonates, and antibiotics. Biological treatments have emerged as a viable alternative for SAPHO patients who do not respond to conventional treatments.

Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis, Palmoplantar Pustulosis, and Neutrophilic Dermatoses: A GRAPPA 2023 Annual Meeting Update

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome and chronic nonbacterial osteomyelitis (CNO) are rare autoinflammatory/autoimmune conditions seen in adults and children. Although osteoarticular manifestations are the primary distinguishing features of SAPHO, over half of patients also have palmoplantar pustulosis (PPP). These and other associated disorders such as acne, inflammatory bowel disease, and hidradenitis suppurativa are characterized, at least in the early stages, by neutrophilic infiltration. The bone and skin manifestations exhibit both innate and adaptive immune responses and therefore share similar pathogenic molecules and overlapping treatment targets. At the Group for Research and Assessment for Psoriasis and Psoriatic Arthritis (GRAPPA) 2023 annual meeting, a 3-part presentation provided an overview of current efforts at establishing consensus on diagnosis/classification, treatment, and core outcome sets for SAPHO/CNO; an overview of PPP in SAPHO and as a standalone condition; and finally, an overview of the role of the neutrophil in these disorders.

The role of cytokines in the pathogenesis of SAPHO syndrome

SAPHO syndrome is a complex inflammatory disorder affecting the skin and bones, characterized by osteomyelitis, acne, and pustulosis. Cytokines play a pivotal role in the pathogenesis of SAPHO syndrome, especially in inflammatory responses and immune regulation. This article reviews the cytokines involved in the pathogenesis of SAPHO syndrome, such as tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), IL-6, IL-10, and transforming growth factor-β (TGF-β), and discusses their potential as intervention points for treatment. These findings elucidate the intricate immune regulatory network of SAPHO syndrome and provide a theoretical foundation for the development of new targeted therapeutic strategies.

A statistical symptomatic evaluation on SAPHO syndrome from 56 cases of confirmed diagnosis and 352 cases of non-SAPHO involvement

OBJECTIVE

To report a statistical evaluation of symptomatology based on 56 cases of SAPHO syndrome and 352 non-SAPHO involvement cases, to propose a symptomatic scoring system in consideration of early warning for SAPHO syndrome.

METHODS

A cohort comprising 56 subjects diagnosed with SAPHO syndrome was reported, as well as 352 non-SAPHO involvement cases, including their chief complaints, skin manifestations, radiological findings, and laboratory tests. We systematically reviewed previous published five representative huge cohorts from different countries to conclude several specific features of SAPHO by comparing with our case series. The score of each specific index is based on respective incidence and comparison of two cohorts was performed.

RESULT

In terms of complaint rates, all subjects of two cohorts suffered from osseous pain, which appeared in the anterior chest wall, spine, and limb which were calculated. In respect to dermatological lesions, SAPHO patients suffered from severe acne, and other patients (82.14%) accompanied with palmoplantar pustulosis. Having received radiological examinations, most SAPHO subjects rather than non-SAPHO involvement cases showed abnormal osteoarticular lesions under CT scanning and more detailed information under whole-body bone scintigraphy. Differences also emerged in elevation of inflammation values and rheumatic markers like HLA-B27. Based on our cases and huge cohorts documented, the early warning standard is set to be 5 scores.

CONCLUSIONS

SAPHO syndrome case series with 56 subjects were reported and an accumulative scoring system for the early reminder on SAPHO syndrome was proposed. The threshold of this system is set to be 5 points. Key Points • Fifty-six patients diagnosed by SAPHO syndrome with detailed symptoms and radiological findings were reported. • Comparison was made between the 56 SAPHO patients and 352 non-SAPHO involvement cases. • An accumulative scoring system for the early reminder on SAPHO syndrome was proposed and the threshold of this system is set to be five points.

The clinical characteristics and prognosis of patients with SAPHO syndrome--a real-world cohort study

OBJECTIVES

We aimed to analyze the clinical characteristics and outcomes of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome.

METHODS

The clinical records of 64 patients with SAPHO syndrome were collected, and the treatment and outcomes of 27 patients were followed up. The patients were divided into three groups according to the site of bone lesions: only anterior chest wall (ACW) involvement, only spinal involvement, and bone lesion involvement at both sites. The clinical characteristics and outcomes were compared. The clinical characteristics of the patients with and without peripheral joint involvement were compared.

RESULTS

Among all patients, 31.25% (20/64) had only ACW involvement, 15.63% (10/64) had only spinal involvement, and 53.12% (34/64) had both ACW and spinal involvement. Peripheral joint involvement was observed in 25.00% (16/64) of the patients. Patients with only spinal involvement were older than those with only ACW involvement (p = 0.006). Patients with both ACW and spinal involvement were older than those with only ACW involvement (p = 0.002) and had a longer diagnosis delay (p = 0.015). Patients with peripheral joint involvement were younger than those without peripheral joint involvement (p = 0.028). During follow-up, 88.89% (24/27) of patients had good outcomes. Twenty-two patients were treated with non-steroidal anti-inflammatory drugs + Iguratimod (IGU), and the outcomes of 90.91% (20/22) improved.

CONCLUSIONS

A relationship may exist between the sites of bone lesions and clinical characteristics of patients with SAPHO syndrome. The clinical outcomes of these patients may be good, and IGU may be effective in treating SAPHO syndrome. Key Points • This study is the first long-term follow-up on the effectiveness of iguratimod in treating patients with SAPHO. • This study revealed that patients with SAPHO and different bone lesion sites may present with different clinical characteristics.

Non-syndromic and Syndromic Severe Acne in Adolescent Patients

Acne is a common skin disorder in adolescents. However, severe acne that is persistent and refractory to conventional treatment or has other associated symptoms should raise suspicion for non-syndromic or syndromic acne.

Treatment and monitoring of SAPHO syndrome: a systematic review

BACKGROUND AND OBJECTIVES

Synovitis acne pustulosis hyperostosis osteitis (SAPHO) is a rare heterogeneous disease of unknown aetiopathology. Externally validated and internationally agreed diagnostic criteria or outcomes and, as a result, prospective randomised controlled trials in SAPHO are absent. Consequently, there is no agreed treatment standard. This study aimed to systematically collate and discuss treatment options in SAPHO.

METHODS

Following 'Preferred Reporting Items for Systematic Reviews and Meta-Analyses' guidance, a systematic literature search was conducted using PubMed, Scopus and Web of Science databases. Prospective clinical studies and retrospective case collections discussing management and outcomes in SAPHO involving five or more participants were included. Articles not published in English, studies not reporting defined outcomes, and studies solely relying on patient-reported outcomes were excluded.

RESULTS

A total of 28 studies (20 observational, 8 open-label clinical studies) reporting 796 patients of predominantly European ethnicity were included. Reported therapies varied greatly, with many centres using multiple treatments in parallel. Most patients (37.1%) received non-steroidal anti-inflammatory drugs alone or in combination. Bisphosphonates (22.1%), conventional (21.7%) and biological (11.3%) disease-modifying antirheumatic drugs were the next most frequently reported treatments. Reported outcomes varied and delivered mixed results, which complicates comparisons. Bisphosphonates demonstrated the most consistent improvement of osteoarticular symptoms and were associated with transient influenza-like symptoms. Paradoxical skin reactions were reported in patients treated with TNF inhibitors, but no serious adverse events were recorded. Most treatments had limited or mixed effects on cutaneous involvement. A recent study investigating the Janus kinase inhibitor tofacitinib delivered promising results in relation to skin and nail involvement.

CONCLUSIONS

No single currently available treatment option sufficiently addresses all SAPHO-associated symptoms. Variable, sometimes descriptive outcomes and the use of treatment combinations complicate conclusions and treatment recommendations. Randomised clinical trials are necessary to generate reliable evidence.

Immunological Characterization of Chronic Nonbacterial Osteomyelitis (CNO) in Adults: A Cross-Sectional Exploratory Study

Chronic nonbacterial osteomyelitis (CNO) is a rare disease spectrum affecting children and adults. Adult CNO may occur as isolated bone inflammation, or with a broad range of extraskeletal features. CNO pathophysiology, including the key drivers of inflammation, remains largely unknown. For pediatric CNO, a role for pro-inflammatory cytokine dysregulation has been proposed, but studies in adults are scarce. We therefore provide immunological characterization of adult CNO. Cross-sectional study in our referral center including adult CNO patients (n = 172) and healthy controls (n = 65). Inflammation parameters and systemic inflammatory based scores(SIBS, including neutrophil/lymphocyte ratio [NLR] and systemic immune inflammation index [SII]) were compared between groups. Cytokine expression was explored with electrochemiluminescent immunoassays in 33 patients, eight healthy controls and 21 osteoporosis patients. Routine inflammation markers were higher in patients than in controls, but generally remained within reference range. Systemic inflammation was more pronounced in patients with additional vertebral involvement as compared to those osteitis in the anterior chest wall alone, in patients with comorbid pustulosis palmoplantaris or psoriasis, and in patients with strongly rather than moderately increased lesional uptake on nuclear imaging. SII was elevated in CNO patients too, but NLR was not. Cytokine expression was generally nondifferential between patients and both control groups, and patients displayed low absolute concentrations of pro-inflammatory cytokines. In this adult CNO cohort, systemic inflammation was generally subtle, but more pronounced in patients with vertebral lesions, associated skin disease, and strongly increased uptake on nuclear imaging. SII was increased in patients compared to healthy controls. Contrasting pediatric studies, we found no increased expression of the pro-inflammatory cytokines that have been proposed to drive the inflammatory cascade, like interleukin-6, -8, and -17 (IL-6, IL-8, and IL-17), and tumor necrosis α (TNF-α). Further studies are needed to evaluate the use of SII in diagnosis and monitoring of CNO, and elucidate the role of cytokine dysregulation in adult disease. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Skin manifestations help identifying different phenotypes of paediatric SAPHO syndrome

OBJECTIVES

to evaluate whether the heterogeneous skin manifestations might influence the disease presentation and outcome of a cohort of SAPHO children.

METHODS

the clinical, serological, imaging and therapeutic data of 14 SAPHO patients, followed between 2001 and 2022 at the Unit for Autoinflammatory diseases at the Gaslini Hospital, were reviewed. According to their cutaneous manifestations, patients were divided into 2 groups: the acne-hidradenitis suppurativa (HS) and the Palmo-Plantar Pustulosis (PPP) group. Data were retrieved from the Eurofever database.

RESULTS

all patients presented bone involvement characterized by Chronic Recurrent multifocal Osteomyelitis (CRMO): 8 patients presented acne-HS while 6 patients had PPP. In the PPP group, all patients were female, characterized by a prepuberal disease onset with osteoarticular manifestations, followed by the appearance of PPP in the following 6 months. This group responded well to the treatments. In the acne-HS group, 7/8 patients were male: the disease onset was characterized by skin manifestations in pubertal age, followed by osteoarticular manifestations in the following year. This group presented a severe refractory skin disease that required in most cases the addition of biological therapies. A literature review confirmed our data highlighting the association males-acne-puberal age and female-PPP-prepuberal age.

CONCLUSION

paediatric SAPHO patients should be mainly stratified according to their skin involvement. In fact, our data suggest that two different skin phenotypes may be identified in SAPHO: the first is constituted by prepuberal females with PPP and a prevalent osteoarticular involvement, while the second by puberal males with a difficult-to-treat acne-HS.

A Case Report on the Atypical Symptoms of the Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO) Syndrome: Could COVID-19 Be a Cause?

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome, a rare disorder with a spectrum of manifestations and overlapping osseous and cutaneous symptoms, shares pathogenesis with various autoimmune diseases. SARS-CoV-2 has been previously linked to various autoimmune diseases like Guillain-Barré syndrome (GBS), a multi-inflammatory syndrome in children (MIS-C), or rheumatoid arthritis, but there is no existing work showing a link between SAPHO syndrome and COVID-19 yet. Here, we present a case of a middle-aged Asian male who presented with minimum swelling of his right second toe, 21 days post-COVID. After a series of investigations, namely, MRI scans, 99mTc-methylene diphosphonate three-phase bone scan, and bone biopsy, followed by a positive culture and sensitivity test of the same toe, a trial of vancomycin was given to the patient to treat bacterial osteomyelitis. This resulted in no improvement, pointing toward a misdiagnosis. A conclusion of sterile osteomyelitis of his right second and third metatarsal heads and phalanges due to SAPHO syndrome, as a possible complication of SARS-CoV-2 infection, was made. There are a number of classification systems for diagnosing this syndrome, one of which was modified by Kahn and was used in our case. Atypical presentations of rare disorders like SAPHO syndrome and their relation to SARS-CoV-2 infection are still to be fully discovered and investigated. Their prevention, timely diagnosis, and management may help in alleviating the discomfort and fear associated with the unknown for the patients.

Clinical spectrum of Cutibacterium acnes infections: The SAPHO syndrome

Cutibacterium acnes, previously known as Proprionobacterium, is a commensal Grampositive bacterium of the skin commonly implicated in prosthetic joint infections. However, it has been documented to play a role in other conditions, including SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, osteitis), a rare autoinflammatory disorder. Diagnosing SAPHO syndrome is cumbersome, as the clinical manifestations are variable and overlap with many inflammatory joint disorders. Herein, we describe a 56-year-old female patient with a presumed diagnosis of longstanding seronegative rheumatoid arthritis and history of C. acnes prosthetic joint infection following revision arthroplasty of the right shoulder. She presented to our clinic with a rash over the upper extremities and trunk and joint symptoms involving the right shoulder. Treatment was initiated with ceftriaxone followed by doxycycline suppressive therapy, with clinical improvement of joint and skin involvement. Symptoms recurred upon brief cessation of antibiotic therapy due to adverse gastrointestinal effects; however, symptoms abated once again upon re-initiation of treatment. Given the patient's cutaneous lesions and longstanding history of arthritis that improved with antimicrobial therapy against C. acnes, the diagnosis of SAPHO syndrome was entertained. The present case demonstrates the clinical challenges of diagnosing SAPHO syndrome and the importance of its consideration on the differential for a patient with osteoarticular and cutaneous features. Additional literature is needed to improve diagnostic criteria and treatment guidelines.

Dermatologic Manifestations of Noninflammasome-Mediated Autoinflammatory Diseases

Autoinflammatory diseases (AIDs) arise from disturbances that alter interactions of immune cells and tissues. They give rise to prominent (auto)inflammation in the absence of aberrant autoantibodies and/or autoreactive T cells. AIDs that are predominantly caused by changes in the inflammasome pathways, such as the NLRP3- or pyrin-associated inflammasome, have gained substantial attention over the last years. However, AIDs resulting primarily from other changes in the defense system of the innate immune system are less well-studied. These noninflammasome-mediated AIDs relate to, for example, disturbance in the TNF or IFN signaling pathways or aberrations in genes affecting the IL-1RA. The spectrum of clinical signs and symptoms of these conditions is vast. Thus, recognizing early cutaneous signs constitutes an important step in differential diagnoses for dermatologists and other physicians. This review provides an overview of the pathogenesis, clinical presentation, and available treatment options highlighting dermatologic aspects of noninflammasome-mediated AIDs.

A case of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome with isolated lesions of the thoracic spine

We report a case of isolated lesions of the thoracic spine attributed to synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. A 55-year-old woman who suffered from 6 months of back pain had vertebral osteomyelitis on magnetic resonance imaging (MRI). There were no laboratory findings suggestive of infection, malignancy, or autoimmune disease. Radiography, computed tomography (CT), and MRI of the thoracic spine showed mixed lesions of sclerosis and erosion, whereas bone scintigraphy did not show accumulation at any site except the thoracic spine. No lesions in the anterior chest wall or sacroiliac joints were apparent from CT and MRI. No lesions other than at the thoracic spine were observed. As the isolated lesions of the thoracic spine were considered not to have resulted from infection, malignancy, or autoimmune disease, the patient was referred to our department for differential diagnosis. Given that isolated sterile hyperostosis/osteitis among adults is included in the modified diagnostic criteria for SAPHO syndrome, we suspected that the mixed lesions of sclerosis and erosion of the thoracic spine in this case may reflect SAPHO syndrome with chronic non-bacterial osteitis (CNO) of the thoracic spine. Treatment with non-steroidal anti-inflammatory drugs (NSAIDs) was initiated and led to alleviation of her back pain, although the thoracic spine lesions remained on the 6-month MRI. Based on the CNO of the thoracic spine and the rapid response to NSAIDs, the final diagnosis was SAPHO syndrome with isolated lesions of the thoracic spine.

Pro and contra: is synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) a spondyloarthritis variant?

PURPOSE OF REVIEW

The purpose of this review is to present the up-to-date evidence on the epidemiology, pathogenesis, musculoskeletal manifestations, and imaging of the synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome and to discuss its relationship with spondyloarthritis (SpA).

RECENT FINDINGS

SAPHO is a rare inflammatory disorder of bone, joints, and skin, with a worldwide distribution that predominantly affects the middle-age adults. The hallmark of the syndrome is a constellation of sterile inflammatory osteitis, hyperostosis, and synovitis involving the anterior chest wall, associated with acneiform and neutrophilic dermatoses, such as palmoplantar pustulosis and severe acne. The axial skeleton, sacroiliac, and peripheral joints can be involved in a similar fashion to SpA. The pathogenesis of the syndrome is multifactorial. The diagnosis is mainly based on the clinical and typical radiological features. The treatment approach is based on the off-label use of antibiotics, bisphosphonates, disease-modifying antirheumatic drugs, and anticytokine biologics.

SUMMARY

The SAPHO syndrome shares common features with SpA-related diseases, yet also shows some unique pathogenetic and clinical features. The nosology of SAPHO remains a subject of controversy, awaiting further research into the pathogenetic and clinical aspects of this syndrome. A better understanding of these aspects will improve the diagnostics and clinical care of patients with SAPHO.

New Insights in the Treatment of SAPHO Syndrome and Medication Recommendations

Synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome is a rare autoinflammatory disease characterized by dermatological disorders and osteoarticular inflammatory lesions. This article reviews the application of biologics and other treatments based on the therapeutic target and the size of molecules in SAPHO syndrome. We found that drugs, especially biologics, have different effects on bone, joint, and skin damage. This may relate to the different inflammatory pathways involved in the osteoarticular and cutaneous symptoms in SAPHO patients. In this study, we provide stratified medication recommendations for SAPHO syndrome. Patients with osteoarticular symptoms can consider tumor necrosis factor blockers, JAK inhibitor, interleukin (IL)-1 inhibitor, and IL-17 inhibitor. Patients with cutaneous symptoms should consider IL-17 and JAK inhibitors. Apremilast, Tripterygium wilfordii Hook F, and bisphosphonates are other effective treatments.

The value of multi-modality imaging in establishing the diagnosis of Adolescent SAPHO

SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis and osteitis) is a rare chronic autoinflammatory disorder of unknown etiology. Radiological investigation, including the use of magnetic resonance imaging and nuclear medicine is pivotal to the diagnosis of SAPHO syndrome. We present a case of a 15-year-old male diagnosed with SAPHO syndrome displaying the classic diagnostic findings of this condition on bone scan and magnetic resonance imaging.

Pharmacological Management of Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis Syndrome Syndrome: A Proposal of a Treatment Algorithm

ABSTRACT

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare chronic disease with marked clinical and radiological heterogeneity. It is characterized by a combination of dermatological and osteoarticular manifestations. The treatment of SAPHO syndrome is not yet codified. It includes several therapeutic options such as anti-inflammatory drugs, bisphosphonates, antibiotics, conventional disease-modifying antirheumatic drugs, and biological treatment.This article aims to provide an updated review of the different pharmacological options for SAPHO syndrome. We also propose a therapeutic algorithm for the management of this disease.

Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO): A Case Report

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) is an uncommon adulthood disorder that presents as focal swellings and pain accompanied by abnormal changes in bone and surrounding soft tissues. X-rays of the involved region are usually insignificant; however, CT and MRI show excellent visualization of the affected structures. Typical radiological images show cortical thickening leading to decreased marrow cavity, bony erosion, and ligament ossifications. Other associated findings are synovitis and joint effusions. It is usually diagnosed on the basis of clinical as well as radiological findings. The treatment initially relies on non-steroidal anti-inflammatory drugs (NSAIDs). Patients showing poor response are started on corticosteroids and disease-modifying antirheumatic drugs (DMARDs). We report two patients who presented with joint swellings. Their workup unmasked the underlying SAPHO, which was managed well with NSAIDs.

Case Report: SAPHO Syndrome Mimicking Bone Metastases During Treatment With Pembrolizumab for Non-small Cell Lung Cancer

A 69-year-old female with recurrent stage IV squamous cell lung carcinoma and metastatic abdominal lymph node but not bone metastases was being treated with pembrolizumab. Four months after starting the recurrent treatment, the tumour reduced in size but she began to complain of back pain and palmar rash. A bone scan showed uptake lesions in the left sternocostal joints and vertebrae, while spine magnetic resonance imaging (MRI) showed multiple lesions in the thoracic vertebrae. Her heterogeneous lesions, such as skin and multiple bone manifestations, were comprehensively diagnosed as SAPHO syndrome by different experts. Furthermore, the SAPHO syndrome was suspected to be an immune-related adverse event induced by pembrolizumab, and pembrolizumab withdrawal and prednisolone treatment were performed. Subsequently, her symptoms improved and the follow-up imaging findings showed that the bone lesions had almost disappeared. This case demonstrates that SAPHO syndrome mimicking bone metastases developed during treatment with pembrolizumab. SAPHO syndrome is rare and bone lesions related to the disease may be misdiagnosed as bone metastases. Therefore, it is important in the future for various physicians to have a better understanding of SAPHO syndrome and to consider the potential relationship between this disease and immunotherapy.

Abundance alteration of nondominant species in fecal-associated microbiome of patients with SAPHO syndrome

Background

SAPHO syndrome is a group of symptoms consisting of synovitis, acne, pustulosis, hyperostosis and osteosis. There is no specific laboratory index assist in the diagnosis of SAPHO because of its highly heterogeneous clinical manifestations. Pathogenic microorganisms had been identified in biopsies of some SAPHO cases and particular gene mutations were also linked to the occurrence of SAPHO. It is largely unknown whether intestinal microbiome plays a role in pathogenesis of SAPHO. To explore the intestinal microbiome structure of SAPHO syndrome, fecal samples from 17 SAPHO patients and 14 healthy controls (HC) were collected for 16S rDNA sequencing.

Results

Our results showed that there was no significant difference in alpha indexes and beta diversity between SAPHO and HC samples, while there were 14 operational taxonomic units (OTUs) in the Wilcoxon rank-sum test and 42 OTUs in the MetagenomeSeq analysis showed significant difference in distribution between the SAPHO and HC groups, 3 of which in Firmicutes were also observed in the random forest analysis and used to construct a receiver operating characteristic curve to evaluate the diagnostic value, the area under the curve was 0.86.

Conclusion

Fecal-associated microbiome in the SAPHO samples was characterized by the alteration in abundance of some nondominant species, and the 3 selected OTUs in Firmicutes could serve as candidate biomarkers for SAPHO syndrome diagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02221-2.

Comparative analysis and differentiation between SAPHO syndrome and spondyloarthropathies using whole-spine MRI

AIM

To determine the imaging characteristics of SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome and seronegative spondyloarthropathies (SpAs) on whole-spine magnetic resonance imaging (WS-MRI) and evaluate the role of WS-MRI in the diagnosis and differentiation of the two diseases.

MATERIALS AND METHODS

Twenty-eight patients with SAPHO and 44 with SpAs were included. All patients were symptomatic and clinically diagnosed with SAPHO or SpAs, and all underwent WS-MRI for comparison of imaging characteristics.

RESULTS

The mean age of the SAPHO patients was 48.7 ± 12.7 years, while that of the SpA patients was 34.7 ± 12.3 years (p<0.001). WS-MRI showed that the frequency of cervical, thoracic, and lumbar spine involvement was 53.6% versus 52.3%, 75% versus 88.6%, and 60.7% versus 63.6%, respectively (p=0.70, 0.13, and 0.80). The frequency of sacroiliac joint involvement was 7.1% and 100% (p<0.001). Continuous spinal involvement accounted for 50% versus 43.2%, 60.7% versus 84.1%, and 39.3% versus 40.9% in the cervical, thoracic, and lumbar vertebrae, respectively (p=0.03). WS-MRI showed that bone marrow oedema of spinal anterior corner was observed in 50% versus 75% (p=0.03). Vertebral body and posterior attachment involvement accounted for 85.7% versus 93.2% and 14.3% versus 34.1% (p=0.3, 0.06). The frequency of bone erosion in mobile spine was 75% and 36.4%, respectively (p=0.02). The frequency of intervertebral disc, endplate, anterior thoracic wall, and paraspinal soft-tissue swelling was 42.9% versus 18.2%, 53.6% versus 22.7%, 85.7% versus 42.2%, and 50% versus 11.4% (p=0.02, 0.00).

CONCLUSIONS

Factors differentiating the two groups at WS-MRI were bone marrow oedema of the spinal anterior corner, bone erosion, and swelling of the intervertebral disc, endplate, anterior thoracic wall, and paraspinal soft-tissue.

Serum Sp17 Autoantibody Serves as a Potential Specific Biomarker in Patients with SAPHO Syndrome

SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome shows a wide variability in musculoskeletal and cutaneous manifestations, and it is therefore underrecognized and misdiagnosed in the clinic due to a lack of specific markers. In this study, we aimed to identify specific biomarkers by screening serum autoantibodies in SAPHO patients with a 17K human whole-proteome microarray. The serum anti-Sp17 autoantibody was identified and verified to be a specific biomarker in patients with SAPHO syndrome. Indeed, the level of the anti-Sp17 autoantibody was significantly increased in patients with active SAPHO compared to patients with an inactive disease and healthy controls (P < 0.05). Additionally, serum anti-Sp17 autoantibody levels correlated with those of serum hypersensitive C-reactive protein (hsCRP), the erythrocyte sedimentation rate (ESR), and β-crosslaps (β-CTx) in patients with active SAPHO disease. Moreover, anti-Sp17 autoantibody levels were markedly decreased after anti-inflammatory treatment with pamidronate disodium, which downregulated levels of hsCRP and ESR in patients with active SAPHO. Thus, serum levels of the anti-Sp17 autoantibody might serve as a specific biomarker for the diagnosis of SAPHO syndrome or for monitoring the disease status.

New Insights into Adult and Paediatric Chronic Non-bacterial Osteomyelitis CNO

Purpose of Review

To describe in detail the clinical synopsis and pathophysiology of chronic non-bacterial osteomyelitis and SAPHO syndrome.

Recent Findings

Chronic non-bacterial osteomyelitis (CNO) has been identified as a disease entity for almost 50 years. This inflammatory bone disorder is characterized by osteolytic as well as hyperostotic/osteosclerotic lesions. It is chronic in nature, but it can present with episodic flairs and phases of remission, which have led to the denomination “chronic recurrent osteomyelitis”, with its severe multifocal form “chronic recurrent multifocal osteomyelitis” (CRMO). For almost three decades, an infectious aetiology had been considered, since especially Propionibacterium acnes had been isolated from bone lesions of individual patients. However, this concept has been challenged since long-term antibiotic therapy did not alter the course of disease and modern microbiological techniques (including PCR) failed to confirm bone infection as an underlying cause. Over recent years, a profound dysregulation of cytokine expression profiles has been demonstrated in innate immune cells of CNO patients. A hallmark of monocytes from CNO patients is the failure to produce immune regulatory cytokines interleukin-10 (IL-10) and IL-19, which have been linked with genetic and epigenetic alterations. Subsequently, a significant upregulation of pro-inflammatory, NLRP3 inflammasome-dependent cytokines (IL-1β and TNF-α), has been demonstrated.

Summary

The current knowledge on CNO, the underlying molecular pathophysiology, and modern imaging strategies are summarized; differential diagnoses, treatment options, outcome measures, as well as quality of life studies are discussed.

The comparison analysis of clinical and radiological features in SAPHO syndrome

OBJECTIVES

The aim was to comparatively assess the clinical and imaging features in patients with SAPHO syndrome.

METHODS

The clinical data, laboratory results, imaging data of forty-six SAPHO patients were reviewed and the SAPHO patients were divided into spinal involvement group and non-spinal involvement group. Fifty patients with ankylosing spondylitis were recruited as control group. The clinical and radiological features of them were analyzed and compared.

RESULTS

Thirty-four of 46 (73.9%) of all the SAPHO patients had spinal involvement. The lesions exhibited as abnormal hyper-intensity signal in vertebral bodies, vertebral body erosion or collapse, bone marrow edema, endplate inflammation, spondyldiscitis, paravertebral ossification, and facet joint involvement. Compared with patients in non-spinal involvement group, the age at disease onset was older (P = 0.033), the disease duration was longer (P = 0.048), and CRP level was elevated (P = 0.047) in patients in spinal involvement group. Compared with patients with ankylosing spondylitis, SAPHO patients were more likely to have cervical vertebra involvement (P = 0.024), endplate inflammation (P = 0.019), and spondyldiscitis (P = 0.001), but less multiple vertebral body and facet joint involvement (P = 0.002). Patients regularly received DMARDS or biologics treatment had symptoms relieved and lesions turned into chronic stage or better than before.

CONCLUSIONS

A total of 73.9% of the SAPHO patients had spinal involvement and the involvement could affect any part of the spine. Cervical vertebral involvement, endplate inflammation, and sponlypodiscitis were more common in SAPHO than in patients with ankylosing spondylitis. In SAPHO patients with spinal involvement, the disease duration was longer and the inflammatory reaction was more intensive. DMARDs and biologics may help to prevent the disease progress.

KEY POINTS

• To the best of our knowledge, this paper is the first one to comparatively study the clinical and radiological features of SAPHO syndrome, especially the characteristics of spinal involvement.

Synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: review and update

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a spectrum of heterogeneous diseases characterized by osteoarticular and dermatological manifestations. Osteitis and hyperostosis are core clinical manifestations in SAPHO syndrome, typically affecting multiple areas and possibly progressing to irreversible osteoarticular damage. Most patients with SAPHO have cutaneous involvement, mainly manifested as palmoplantar pustulosis and severe acne. Systemic manifestations are uncommon but occasionally reported. Epidemiological studies suggest the annual prevalence of SAPHO syndrome varies from 0.00144 in 100,000 in Japanese individuals to fewer than 1 in 10,000 in White individuals. The precise etiopathogenesis of SAPHO remains unclear, but it is generally considered an autoinflammatory syndrome that may be related to various etiologies, such as immune dysfunction, infection and genetic predisposition. Owing to the relapsing-remitting disease course, the goal of management is to improve clinical symptoms and prevent disease progression. Various treatments, including nonsteroidal anti-inflammatory drugs, conventional disease-modifying antirheumatic drugs, bisphosphonates, biologics, and antibiotics, are promising options for alleviating the disease.

Genetic variants in FBLIM1 gene do not contribute to SAPHO syndrome and chronic recurrent multifocal osteomyelitis in typical patient groups

Background

Syndrome of synovitis acne pustulosis hyperostosis osteitis (SAPHO) and chronic recurrent multifocal osteomyelitis (CRMO) present two diseases of a dermatologic and rheumatologic spectrum that are variable in manifestation und therapeutic response. Genetic risk factors have long been assumed in both diseases, but no single reliable factor has been identified yet. Therefore, we aimed to clinically characterize a patient group with syndrome of synovitis acne pustulosis hyperostosis osteitis (SAPHO) (n = 47) and chronic recurrent multifocal osteomyelitis (CRMO)/ chronic non-bacterial osteomyelitis (CNO) (n = 9) and analyze a CRMO candidate gene.

Methods

Clinical data of all patients were collected and assessed for different combinations of clinical symptoms. SAPHO patients were grouped into categories according to the acronym; disease-contribution by pathogens was evaluated. We sequenced coding exons of FBLIM1.

Results

Palmoplantar pustular psoriasis (PPP) was the most common skin manifestation in CRMO/CNO and SAPHO patients; most SAPHO patients had sterno-costo-clavicular hyperostosis. The most common clinical category of the acronym was S_PHO (n = 26). Lack of pathogen detection from bone biopsies was more common than microbial isolation. We did not identify autosomal-recessive FBLIM1 variants.

Conclusions

S_PHO is the most common combination of symptoms of its acronym. Genetic analyses of FBLIM1 did not provide evidence that this gene is relevant in our patient group. Our study indicates the need to elucidate SAPHO’s and CRMO/CNO’s pathogenesis.

Exosomal proteome from the serum, bone marrow, and palm and toe pustular skin tissues of a single patient with SAPHO syndrome

Exosome proteomic analysis may reveal differentially abundant proteins that are of significance for clarifying the pathogenesis of SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis) syndrome. Exosomes were isolated from the serum, bone marrow and skin tissue of the palm and toe pustular areas in a unique patient with SAPHO syndrome. The exosomes were not different from those of healthy subjects in size (114.1 ± 73.7 nm) or morphology. Label-free exosome proteomic analysis identified 198 more abundant proteins and 183 less abundant compared with those of healthy subjects. Gene ontology enrichment analysis revealed that these proteins were involved in binding with a variety of biological molecules and participated in biological processes related to autoimmunity or inflammation. A total of 243 KEGG (Kyoto Encyclopedia of Gene and Genomes) pathways were enriched, of which 43 were related to immune function. It was speculated that five differentially abundant proteins, Mitogen-activated protein kinase 1 (MAPK1/MK01), Tyrosine protein kinase (SYK), Integrin beta-3 (ITB3), Serine/threonine-protein phosphatase 2a catalytic subunit alpha isoform (PP2AA) and Serine/threonine-protein phosphatase 2a 65 kDa regulatory subunit A beta isoform (2AAB), associated with multiple KEGG pathways, forms an interaction network that may be involved in the occurrence, development and prognosis of SAPHO syndrome. SIGNIFICANCE: Exosomes of SAPHO syndrome patient were not significantly different from those of healthy subjects in size and morphology. Label-free proteomic analysis of exosomal proteins in patient with SAPHO syndrome speculated 5 proteins MAPK1, SYK, ITB3, PP2AA and 2AAB, which may be involved in the occurrence, development and prognosis of SAPHO syndrome by binding with other biological molecules. It is speculated for the first time that proteins Histone H2A type 1-J and Histone H4 were related to SAPHO syndrome. Clinic relevance. Exosome proteomics can suggest novel pathological data in patients with SAPHO.

The role of Cutibacterium acnes in auto-inflammatory bone disorders

Chronic nonbacterial osteomyelitis (CNO) and SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome are auto-inflammatory disorders manifesting as chronic inflammation of bones and joints, which in SAPHO is often accompanying by skin changes. The aetiology of these diseases is unknown, but includes genetic, infectious and immunological components. It has been proposed that Cutibacterium (formerly Propionibacterium) acnes plays a role in the pathogenesis. In this review, we summarise reported cases of CNO or SAPHO syndrome in which C. acnes has been isolated from bones. To identify cases, a search was done in May 2018 using the MEDLINE Ovid interface (1946 to present). We found 14 publications reporting 98 patients with auto-inflammatory bone disorders, of whom 48 (49%) had positive bone biopsies for C. acnes. This bacterium was more frequently isolated from open biopsies than percutaneous ones (43/69 (62%) vs 1/7 (14%); p = 0.04) and biopsies were more frequently positive in patients who presented with simultaneous skin manifestations (19/36 (53%) vs 4/12 (33%); p = 0.03).Conclusion: In patients with CNO or SAPHO, C. acnes can be isolated from open biopsies suggesting that in these patients, C. acnes might be a pathogen rather than a contaminant. The fact that biopsies are more frequently positive in patients who present with simultaneous skin manifestations suggests that these individuals might have a genetic predisposition for impaired clearance of C. acnes. What is known • Chronic nonbacterial osteomyelitis (CNO) and SAPHO (synovitis, acne, pustulosis, hyperostosis and osteitis) syndrome are auto-inflammatory disorders manifesting as inflammation of bones. Both diseases are an important differential diagnosis in children who present with symptoms of (multifocal) osteomyelitis. • The pathogenesis of CNO and SAPHO is multifactorial emcompassing genetic, infectious and immunological components, including interleukin (IL)-1 dysregulation. There is a controversy as to whether Cutibacterium (formerly Propionibacterium) acnes plays a role in the aetiology of CNO and SAPHO. It has been postulated that the presence of C. acnes might trigger auto-inflammatory chronic inflammation in genetically predisposed individuals. What is new • In patients with CNO or SAPHO, C. acnes can be isolated more frequently from open biopsies, than from percutaneous ones, suggesting that C. acnes might be a pathogen rather than a contaminant. • Biopsies are more frequently positive in patients who present with simultaneous skin manifestations suggesting that these individuals might have a genetic predisposition for impaired clearance of C. acnes. Impaired C. acnes clearance likely leads to increased IL-1 beta (β) production by skin cells, bone cells and phagocytes, which is one of the main cytokines underlying chronic inflammatory bone disorders.

Diagnostic value of ultrasonography in synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome: A case report

RATIONALE

Synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome is a rare condition that affects the skin, bones, and joints. Diagnosis of SAPHO syndrome is established based on clinical manifestations and imaging features on radiography or magnetic resonance imaging.

PATIENT CONCERNS

We report a 44-year-old male with a 20-year history of pustulosis who presented with pain in the lower extremities. Plain radiography demonstrated hyperostosis with subperiosteal erosions in the right tibia. Magnetic resonance imaging and computed tomography showed inflammatory accumulation, whereas musculoskeletal ultrasonography clearly depicted a periosteal reaction, osteitis, and enthesitis with abnormal blood flow in the surface of the right tibia.

DIAGNOSES

A diagnosis of SAPHO syndrome was made.

INTERVENTIONS

The patient was treated with combination therapy comprising prednisolone, methotrexate, and infliximab, which resulted in clinical improvement.

OUTCOMES

The elevated levels of C-reactive protein and matrix metalloproteinase-3 normalized, and the abnormal ultrasonographic findings disappeared.

LESSONS

The present case report demonstrates that multiple imaging modalities are important for the definitive diagnosis of SAPHO syndrome. Ultrasonography might be a useful tool for evaluating local musculoskeletal inflammation in patients with SAPHO syndrome.

Serum levels of proinflammatory, anti-inflammatory cytokines, and RANKL/OPG in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome

OBJECTIVE

To measure the expression of proinflammatory, anti-inflammatory cytokines, and receptor activator NK-κB ligand (RANKL)/osteoprotegerin (OPG) in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome, and to assess the relationship between those factors and disease activity.

METHODS

We studied 30 cases of SAPHO syndrome and 15 healthy controls. According to the Visual Analogue Scale (VAS) pain scores and Bath Ankylosing Spondylitis Activity Index (BASDAI), patients were divided into active group and stable group. The serum levels of IFN-γ, TNF-α, TGF-β1, IL-1β, IL-4, IL-6, IL-8, IL-17A, IL-22, RANKL, and OPG were determined by ELISA.

RESULTS

The active group IL-6 (2.34 ± 1.31 pg/ml), IL-8 (36.41 ± 12.93 pg/ml), and IL-17A (29.17 ± 4.01 pg/ml) levels were significantly higher than those in the stable group (p < .01) and healthy controls (p < .01). RANKL in active group (73.43 ± 57.07 pg/ml) was significantly higher than the ones in other groups (p < .0001), with increased RANKL/OPG ratio in the active group compared with other groups (p < .05). While the level of TGF-β1 in the active group was significantly lower than that in the stable and control groups (p < .0001). There was no significant difference with clinical significance were found in IFN-γ, TNF-α, IL-1β, IL-4, IL-22, and OPG.

CONCLUSION

In active SAPHO patients, there was an anomaly of proinflammatory and anti-inflammatory cytokines balance in SAPHO syndrome.

Case report: successful treatment of refractory SAPHO syndrome with the JAK inhibitor tofacitinib

INTRODUCTION

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is an autoinflammatory disorder without standardized treatment. Janus kinase (JAK) inhibitors can block a range of cytokines and might possess significant anti-inflammatory activity. Here, we report the first case of efficacious treatment of refractory SAPHO syndrome with the JAK inhibitor tofacitinib.

CASE PRESENTATION

A 44-year-old woman presented with arthralgia in the right wrist and complained of having difficulty in doing housework. Symptoms were unresponsiveness to nonsteroidal anti-inflammatory drugs, disease-modifying antirheumatic drugs, and tumor necrosis factor inhibitors. A diagnosis of SAPHO syndrome was made based on previous dermatological and osteoarticular manifestations and bone scintigraphy findings. Oral treatment with tofacitinib at 5 mg twice daily in combination with the basic methotrexate treatment was initiated. After 4 weeks of using tofacitinib, the patient reported marked improvement of symptoms and also reported being competent in completing housework.

CONCLUSIONS

The efficacy of JAK inhibitors in treating refractory SAPHO syndrome should be noted.

[Parkinson's disease associated with SAPHO syndrome: a case report]

A 77-year-old woman with Parkinson's disease presented with left chest pain. Physical examination revealed tenderness at her second left sternocostal joint. There was no skin rash. Chest CT revealed hyperostosis of the sternocostal joint, and cervical MRI showed vertebral osteosclerosis and osteolysis. 99mTc-MDP bone scintigraphy showed an increased activity in the sternocostal joint and vertebral column. The patient was diagnosed with SAHPO syndrome according to the diagnostic criteria. Her chest pain was relieved after oral administration of nonsteroidal anti-inflammatory drugs. Although pain is a common non-motor symptom of Parkinson's disease, chest pain is relatively rare, according to a previous reports. When patients with Parkinson's disease complain of chest pain, physicians should make an appropriate differential diagnosis after excluding emergent cardiovascular disease. To the best of our knowledge, this is the first report of Parkinson's disease associated with SAPHO syndrome. The relationship between the two diseases is unclear. However, peripheral inflammation is known to exacerbate ongoing neuronal damage in neurodegenerative diseases, such as Parkinson's disease. Therefore, systemic inflammation of SAPHO syndrome may affect the disease course of Parkinson's disease.

F-18 FDG PET/CT in 26 patients with SAPHO syndrome: a new vision of clinical and bone scintigraphy correlation

Backgrounds

Whole-body bone scintigraphy (WBBS) and MRI are widely used in assessment of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. However, the value of F-18 fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in SAPHO syndrome was unclear. The aim of this study was to characterize the manifestation of SAPHO syndrome on ¹⁸F-FDG PET/CT and explore its relationship with clinical symptoms and WBBS.

Methods

Twenty-six patients who suffered from SAPHO syndrome and had undergone whole-body ¹⁸F-FDG PET/CT were recruited in Peking Union Medical College Hospital from 2004 to 2016. Clinical manifestations and laboratory findings were recorded for all patients. Imaging data on 18F-FDG PET/CT and WBBS were collected and analyzed retrospectively.

Results

All the 26 patients (20 females and 6 males) exhibited skeletal abnormalities on ¹⁸F-FDG PET/CT. Multiple skeletal lesions affecting the anterior chest wall or spine with low to moderate ¹⁸F-FDG uptake and coexistence of osteolysis and osteosclerosis presented as the typical features of SAPHO syndrome. Sixteen (61.5%) patients had abnormal ¹⁸F-FDG uptake outside the osteoarticular system. PET scan had moderate to substantial agreement with CT and WBBS in revealing lesions in the anterior chest wall and axial skeleton. Nonetheless, the correlation between increased ¹⁸F-FDG uptake and clinical symptoms was weak.

Conclusions

SAPHO syndrome exhibits characteristic features on ¹⁸F-FDG PET/CT. It showed comparable capacity in revealing skeletal lesions with bone scintigraphy.

Electronic supplementary material

The online version of this article (10.1186/s13018-018-0795-0) contains supplementary material, which is available to authorized users.

Letters to the Editor: Refractory SAPHO syndrome with positive Th17-related pathway immunohistochemistry staining

A 34-year-old female was presented with left clavicle mass, recurrent ostalgia, and vesiculo-pustular rash in hands and feet. During 9 years of disease duration, she received first- and second-line therapies, however, with poor respond to non-steroidal anti-inflammatory drugs and disease-modifying antirheumatic drugs. Upon arrival, the physical examination revealed right clavicle swollen with severe tenderness and poor lumbar motility. Laboratory evaluation revealed elevated inflammatory indicators and imaging examinations revealed multiple bone erosion and sclerosis. The immunohistochemical staining of the bone biopsy presented the elevation of the Th17-related cytokines interleukin (IL)-6, IL-17, and IL-23, and negative expression of tumor necrosis factor (TNF)-β and receptor activator NK-κB ligand (RANKL). The immunohistochemical staining of target tissue revealed possible physiologic pathway and potential treatment target. Th17-related pathway might function as the central pathway of pathophysiologic process in SAPHO syndrome.

Skin symptoms as diagnostic clue for autoinflammatory diseases

Autoinflammatory disorders are immune-mediated diseases with increased production of inflammatory cytokines and absence of detectable autoantibodies. They course with recurrent episodes of systemic inflammation and fever is the most common symptom. Cutaneous manifestations are prevalent and important to diagnosis and early treatment of the syndromes. The purpose of this review is to emphasize to dermatologists the skin symptoms present in these syndromes in order to provide their early diagnosis.

SAPHO syndrome associated with hidradenitis suppurativa and pyoderma gangrenosum successfully treated with adalimumab and methotrexate: a case report and review of the literature

SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome is a rare inflammatory condition describing the combination of skin, bone, and joint manifestations that has a heterogeneous presentation. We report a case of severe SAPHO syndrome in association with hidradenitis suppurativa and pyoderma gangrenosum in a 27-year-old male. The patient had an initial migratory arthritis affecting the knees, ankles, metacarpophalangeal joints, proximal interphalangeal joints, wrists, shoulder, and lower back, which progressed to a persistent arthritis and swelling at the sternum, shoulders, wrists, hands, feet, and lower back. Radiographic changes were consistent with the diagnosis of SAPHO syndrome. Serum proinflammatory cytokine levels were significantly elevated and improved substantially after 3 months of therapy. Rationale for therapy in this patient was the observation that tumor necrosis alpha antagonists have been successfully used in SAPHO syndrome, and since arthropathy was so prominent in our patient, we elected to use adalimumab combined with methotrexate.

A case of bronchiolitis obliterans organising pneumonia associated with SAPHO (synovitis-acne-pustulosis-hyperostosis-osteitis) syndrome

A 57-year-old woman with SAPHO (synovitis-acne-pustulosis-hyperostosis-osteitis) syndrome presented with recurrent episodes of pneumonia. She was treated with multiple courses of antibiotics with no success. The transbronchial biopsy undertaken via bronchoscopy revealed organising pneumonia (OP). She was treated with steroids and responded well with full clinical recovery and normalisation of her chest X-ray.To our knowledge, this is the first reported case of OP in association with SAPHO syndrome. This case report highlights the importance of considering OP in patients with SAPHO syndrome who present with chest infection.

Clinical heterogeneity of SAPHO syndrome: challenging diagnose and treatment

Synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO) syndrome is a rare disease which is often misdiagnosed and under-recognized, because of its peculiar and heterogeneous clinical presentation. Its main features consist of cutaneous and osteoarticular manifestations, the latter affecting more often the anterior chest wall and having typical radiologic findings. There are no validated diagnostic criteria for SAPHO and no guidelines for treatment, due mainly to its rarity; as a consequence, therapy is empirical and aimed to control pain and modifying inflammatory process. To date, the use of anti-TNF agents has been proved to be a valid alternative for patients unresponsive to conventional treatments, such as NSAIDs, corticosteroids, DMARDs and biphosphonates. The clinical heterogeneity of the disease, possibly due to differences in pathogenic mechanism of different manifestations, is challenging for both diagnosis and treatment, which should aim to control both skin and bone involvement in different clinical subsets. Here, we summarize the current status of knowledge about the SAPHO syndrome and present two cases of patients with very different disease manifestations, suggesting the need for personalized treatment.

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome with remarkably elevated serum IgG4

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare inflammatory disorder with unknown etiology, while the evidence of the association between IgG4 and inflammatory disorders is accumulating. We present the first report of a patient with SAPHO syndrome with remarkably elevated serum IgG4. The clinical features of this 45-year-old male patient included pain of the anterior chest wall and right elbow, bone marrow edema in the ulna suggested by magnetic resonance imaging (MRI), the “bull’s head” sign on the bone scintigraphy, and remarkably increased IgG4 and interleukin-6. This report may indicate a spectrum of diseases with serum IgG4 elevation broader than previously reported. Moreover, it also provides information on the underlying abnormal immune response in SAPHO syndrome.

Paradoxical SAPHO syndrome observed during anti-TNFα therapy for Crohn's disease

Currently, anti-TNFα antibodies are used to treat Crohn’s disease. We report on a 45-year-old Japanese female with Crohn’s disease developing SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome following exposure to the anti-TNFα antibody adalimumab. Initially, adalimumab induced remission, but the patient showed SAPHO syndrome 11 weeks following the start of adalimumab therapy for the first time. Cutaneous and articular involvement were exacerbating the condition, so adalimumab was discontinued and the patient was put on low-dose methotrexate to control her symptoms. To our knowledge, this is the first report of SAPHO syndrome occurring during anti-TNF therapy, which is thought to be a paradoxical response to adalimumab.

SAPHO, autophagy, IL-1, FoxO1, and Propionibacterium (Cutibacterium) acnes

Overt infection by Propionibacterium acnes is lacking in many SAPHO syndromes, and antibiotics have only a transient and incomplete effect, either in SAPHO syndrome or acne. As several auto-inflammatory bone disorders sharing overproduction of IL-1β can mimic SAPHO, this syndrome could partly depend on genetically encoded overproduction of IL-1β. However, cyclic intracellular infections, mostly by P. acnes, can contribute to the enhanced IL-1β release by some skin cells, and probably by bone cells. P. acnes is indeed a powerful trigger of NLRP3-inflammasome activation and IL-1β, leading to osteitis and enhanced mesenchymal cells differentiation in osteoblasts. Recent advances in the understanding of acne suggest that first steps of this disorder are not driven by P. acnes, but by a relative deficiency of FoxO1 within the nucleus of sebaceous cells. A similar defect of FoXO1 in bone cells should also be sought in SAPHO, since repression of FoxO1 gene is found in lesional psoriasis skin, and is associated with an increased number of osteoblasts and high bone mass in mice. FoxO1 selectively promotes IL-1β production, so that its downregulation could help some P. acnes t escape innate immunity and persist in a latent state in bone cells, including mesenchymal stem cells. However, P. acnes itself possibly contributes to FoxO1 downregulation, like H. pylori infection which induces nuclear inactivation of FoxO1 in human gastric cells to slow down autophagic clearance. As bisphosphonates, which often improve SAPHO syndromes, enhance autophagy, it may be worth testing whether their combination with antibiotics is synergistic in SAPHO syndromes.