Imaging for Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO) Syndrome

An improved understanding of pediatric chronic nonbacterial osteomyelitis pathophysiology informs current and future treatment

Chronic nonbacterial osteomyelitis (CNO) is an autoinflammatory bone disease that primarily affects children and young people. It can cause significant pain, reduced function, bone swelling, and even (vertebral body) fractures. Because of a limited understanding of its pathophysiology, the treatment of CNO remains empiric and is based on relatively small case series, expert opinion, and personal experience. Several studies have linked pathological NOD-kike receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome activation and the resulting imbalance between pro- and anti-inflammatory cytokine expression with CNO. This agrees with elevated pro-inflammatory (mostly) monocyte-derived protein signatures in the blood of CNO patients that may be used as future diagnostic and/or prognostic biomarkers. Recently, rare variants in the P2RX7 gene, encoding for an ATP-dependent transmembrane channel, were linked with increased NLRP3 inflammasome assembly and prolonged monocyte/macrophage survival in CNO. Although the exact molecular mechanisms remain unclear, this will inform future target-directed and individualized treatment. This manuscript reviews most recent developments and their impact on diagnostic and therapeutic strategies in CNO.

Current and future advances in practice: SAPHO syndrome and chronic non-bacterial osteitis (CNO)

Synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO) syndrome is a rare, underdiagnosed disease with a wide clinical spectrum. Sterile bone inflammation, predominantly of the anterior chest, and skin manifestations (palmoplantar pustulosis, psoriasis vulgaris and acne) are the key features of SAPHO, which shares certain similarities with SpA. SAPHO is closely related to paediatric chronic non-bacterial osteitis (CNO), a spectrum of autoinflammatory bone diseases. The aetiology of SAPHO is considered multifactorial based on a complex interplay of genetic, immune and infectious factors. Despite the increasing awareness of SAPHO/CNO, diagnostic delay is common, as validated classification and diagnostic criteria are lacking. Treatment of SAPHO represents a challenge and includes anti-inflammatory drugs, antibiotics, bisphosphonates, synthetic conventional DMARDs and off-label use of anti-cytokine biologics and Janus kinase inhibitors. This review summarizes the current diagnostic and practical treatment approach to SAPHO/CNO and highlights the ongoing research endeavours concerning the definition and validation of diagnostic criteria, core domains and treatment.

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.

Defining the imaging diagnostic criteria for adult chronic non-bacterial osteitis

Osteitis of the sternocostoclavicular (SCC) region, referred to as sternocostoclavicular hyperostosis (SCCH), is the clinical expression of chronic non-bacterial osteitis (CNO) in adults with this rare chronic auto-inflammatory disorder of the axial skeleton. The diagnosis is based on distinctive computerized tomography (CT) features of sclerosis and hyperostosis of the SCC region, and local increases in osteoid formation visualized by high radiopharmacon uptake on skeletal scintigraphy but clear radiologic diagnostic criteria are lacking. In a cross-sectional study, CT scans and whole-body skeletal scintigraphy images obtained in 169 patients seen at the Center for Bone Quality of the Leiden University Medical Center between 2008 and 2018 with a suspected diagnosis of CNO of the SCC region were re-evaluated by 2 skeletal radiologists and 2 nuclear physicians. The diagnosis was confirmed in 118 (70%) predominantly female patients (n = 103, 89.2%); median age at first symptoms 45 years (range 20-73). The diagnosis was excluded in the remaining 51 "non-CNO" patients. Increased radiopharmacon uptake at the SCC region was observed in 82% CNO patients, with the manubrium sterni having the highest predictive ability to discriminate on both imaging modalities. The prevalence of sclerosis of the clavicles, manubrium and first ribs was significantly higher in CNO patients (P < 0.001). Hyperostosis was not observed in non-CNO patients. 46 CNO versus only 2 non-CNO patients had costoclavicular ligament calcification. Our findings identify CT scan features of sclerosis and hyperostosis of manubrium sterni, medial end of clavicles and first ribs, and calcification of costoclavicular ligaments, associated with increased tracer uptake on skeletal scintigraphy at the SCC region, specifically manubrium sterni, as well-defined imaging diagnostic criteria for adult CNO. Pitfalls encountered in the diagnosis of CNO are highlighted. These defined imaging diagnostic criteria for adult CNO should facilitate the diagnosis of this rare auto-inflammatory bone disease across the spectrum of its early to late stages.

Synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome with cranial bone involvement: Case report and literature review

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare autoimmune inflammatory disease characterized by osteoarticular and dermatological manifestations. The most common osteoarticular manifestations involve the anterior chest wall, axial skeleton, and long bones. Cranial bone involvement is less reported in SAPHO syndrome. We herein present three cases of SAPHO syndrome with cranial bone involvement, and review the previous literature on similar manifestations. It was revealed that SAPHO syndrome could lead to cranial bone involvement, which could involve the dura mater, leading to hypertrophic pachymeningitis, but the outcome is usually good. Janus kinase inhibitors may be a potential treatment option.

Prospective Comparison of the Imaging Value of 99m Tc-MDP Bone Scan and 68 Ga-FAPI-04 PET/CT in Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis Syndrome

PURPOSE

This study aimed to explore the imaging value of 68 Ga-FAPI-04 PET/CT in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome and compare it with that of 99m Tc-MDP bone scan.

METHODS

Nineteen participants with SAPHO syndrome underwent 68 Ga-FAPI-04 PET/CT and 99m Tc-MDP bone scan. Demographic data and clinical features were recorded, SAPHO imaging features were analyzed, and the osteoarticular lesion detection rate in both methods was calculated.

RESULTS

This prospective study recruited 4 men and 15 women aged 52.4 ± 8.6 years. The anterior chest wall was involved in all participants (100%). Palmoplantar pustulosis was the most common (36.8%) skin symptom. 99m Tc-MDP bone scan and 68 Ga-FAPI-04 PET/CT together detected 84 osteoarticular lesions, of which 91.7% (77/84) were detected by the former and 96.4% (81/84) by the latter. Furthermore, 68 Ga-FAPI-04 PET/CT detected 5 cases of knee and hip joint synovitis.

CONCLUSIONS

68 Ga-FAPI-04 PET/CT was more sensitive than 99m Tc-MDP bone scan when evaluating osteoarticular lesions in SAPHO syndrome and could also evaluate synovial lesions. 68 Ga-FAPI-04 PET/CT could be a good imaging method for SAPHO syndrome but requires further verification in a more extensive research cohort.

Comparison of 68Ga-DOTA-FAPI-04 and 18F-FDG PET/CT in Patients With SAPHO Syndrome

PATIENTS AND METHODS

68Ga-DOTA-FAPI-04 PET/CT was performed on a cohort of 21 patients with known SAPHO syndrome. All patients underwent 68Ga-DOTA-FAPI-04 and 18F-FDG PET/CT on 2 consecutive days. The positive rates of the PET/CT scans at the sites of the osteoarticular symptom, the uptake values, and agreement with clinical osteoarticular symptom were compared.

RESULTS

A total of 38 sites of involvement were detected. 18F-FDG PET/CT revealed 28 lesions. In contrast, 68Ga-DOTA-FAPI-04 PET/CT detected not only all lesions shown on 18F-FDG PET/CT but additional 10 lesions. 68Ga-DOTA-FAPI-04 scan also demonstrated significantly higher uptake and target-to-background ratio than 18F-FDG studies in the skeletal involvements. The agreement between 68Ga-DOTA-FAPI-04-positive lesions and current osteoarticular lesions was substantial (κ = 0.79, P < 0.001), whereas 18F-FDG had low to moderate agreement with clinical symptoms (κ = 0.52, P < 0.001).

CONCLUSIONS

68Ga-DOTA-FAPI-04 has potential as a promising imaging agent for the evaluation of SAPHO syndrome.

Successful Treatment of SAPHO Syndrome Complicated with Ankylosing Spondylitis by Secukinumab: A Case Report

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is characterized by a wide range of dermatological and musculoskeletal manifestations, and its outcome has recently been improved greatly by optimizing management. However, the treatment strategies are not standardized and require further refinement. Secukinumab, a fully human monoclonal antibody targeting IL-17A, is approved for the treatment of autoimmune psoriasis, psoriatic arthritis (PsA), and ankylosing spondylitis (AS). Here, a 53-year-old man was diagnosed with AS, and he presented scattered pustulosis in both hands and feet with a 5-year history of recurrent lumbosacral area pain and abnormal pain in the neck and front chest area. Secukinumab improved the patient's cutaneous lesion and prevented musculoskeletal pain by substituting adalimumab. Although only a few cases have been reported that secukinumab can effectively treat SAPHO syndrome complicated with AS, the efficacy remains controversial. Therefore, we hope to provide a novel valuable therapeutic strategy for SAPHO syndrome management, particularly in patients with skin lesions.

Severe Cervicodynia in a Patient With Pustules on the Palms

A 51-year-old man had severe neck pain and pustules on both hands. What is your diagnosis?

Quantitative bone SPECT/CT for evaluating treatment response in patient with sternoclavicular arthritis

We report here a case of sternoclavicular arthritis due to SAPHO syndrome in a 60-year-old female in which quantitative values determined using bone SPECT/CT were useful to evaluate response. After celecoxib and alendronate sodium hydrate therapy, the chief complaints were well relieved and post-treatment Tc-99m HMDP bone SPECT/CT examination showed decreased uptake. The maximum standardized uptake value (SUV), peak SUV, mean SUV, metabolic bone volume, and total bone uptake of the untreated lesion were 18, 16, 10, 17 mL, and 180, respectively, which were decreased to 8, 7, 5, 15 mL, and 75, respectively, after the treatment. In comparison with pre-treatment situation, those parameters were decreased by -56%, -56%, -50%, -12%, and -58%, respectively, following celecoxib and alendronate sodium hydrate therapy, likely reflecting treatment response. Quantitative bone SPECT/CT may be useful to evaluate joint inflammatory activity and treatment response in a patient with osteoartritis.

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.

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome of femoral neoplasm-like onset: a case-based review

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is an umbrella term covering a constellation of bone lesions and skin manifestations, but has rarely been clarified in the clinic. We report a 28-year-old woman who had initial onset of SAPHO syndrome with involvement of the femur, and she experienced a tortuous diagnostic course. We also performed a literature review of SAPHO syndrome cases involving the femur and summarize several empirical conclusions by integrating previous findings with our case. Furthermore, we propose our perspective that ailment of the skin caused by infection of pathogens might be the first hit for triggering or perpetuating the activation of the immune system. As a result, musculoskeletal manifestations are probably the second hit by crosstalk of an autoimmune reaction. The skin manifestations preceding bone lesions can be well explained. Current interventions for SAPHO syndrome remain controversial, but drugs aiming at symptom relief could serve as the first preference for treatment. An accurate diagnosis and appropriate treatment can cure patients in a timely manner. Although the pathogenesis of SAPHO syndrome remains to be determined, physicians and surgeons still need to heighten awareness of this entity to avoid invasive procedures, such as frequent biopsies or nonessential ostectomy.

PET/MRI in paediatric disease

Nuclear medicine and molecular imaging have a small but growing role in the management of paediatric and neonatal diseases. During the past decade, combined PET/MRI has emerged as a clinically important hybrid imaging modality in paediatric medicine due to diagnostic advantages and reduced radiation exposure compared to alternative techniques. The applications for nuclear medicine, radiopharmaceuticals and combined PET/MRI in paediatric diagnosis is broadly similar to adults, however there are some key differences. There are a variety of clinical applications for PET/MRI imaging in children including, but not limited to, oncology, neurology, cardiovascular, infection and chronic inflammatory diseases, and in renal-urological disorders. In this article, we review the applications of PET/MRI in paediatric and neonatal imaging, its current role, advantages and disadvantages over other hybrid imaging techniques such as PET/CT, and its future applications. Overall, PET/MRI is a powerful imaging technology in diagnostic medicine and paediatric diseases. Higher soft tissue contrasts and lower radiation dose of the MRI makes it the superior technology compared to other conventional techniques such as PET/CT or scintigraphy. However, this relatively new hybrid imaging has also some limitations. MRI based attenuation correction remains a challenge and although methodologies have improved significantly in the last decades, most remain under development.

Tripterygium wilfordii Hook F. in the treatment of synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: a clinical trial

OBJECTIVE

This study aimed to investigate the efficacy and safety of Tripterygium wilfordii Hook F. (TwHF) in the treatment of osteoarticular lesions in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome.

METHODS

Eligible SAPHO patients were recruited to this single-center trial to receive 12-week TwHF treatment. Two dose groups (1.0-mg/kg/day group and 1.5-mg/kg/day group) were designed and patients were allocated (1:1) to these two groups. The primary endpoint was the change from baseline in Ankylosing Spondylitis Disease Activity Score on the basis of C-reactive protein level (ASDAS) at week 12.

RESULTS

All the 30 included patients completed the trial. At week 12, both dose groups showed significant change from baseline in ASDAS (1.0-mg/kg/day group: - 1.34 (1.10), p = 0.000; 1.5-mg/kg/day group: - 1.53 (1.19), p = 0.000). Similar improvement was also found in the Visual Analogue Scale in global osteoarticular pain, Bath Ankylosing Spondylitis Disease Activity Index, and other efficacy measures. The results showed a fast-acting characteristic of TwHF that the maximum efficacy was achieved within the first 2-4 weeks and maintained at a stable level for the rest of the study. No significant differences were observed between the two dose groups under the current sample size. TwHF was well tolerated that no severe adverse events or irregular menstruation were recorded, except for one patient who developed severe alanine aminotransferase elevation at the last follow-up and has stopped the TwHF treatment after the 12-week follow-up.

CONCLUSIONS

TwHF should be considered for the treatment of osteoarticular lesions in SAPHO syndrome in clinical practice because of significant efficacy, reliable safety, and high socioeconomic value.

TRIAL REGISTRATION

ChiCTR1900025912 Key points • This is the first clinical trial to evaluate Tripterygium wilfordii Hook F. (TwHF) in the treatment of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. • Twelve-week TwHF treatment in both dose groups designed (1.0-mg/kg/day group and 1.5-mg/kg/day group) was well tolerated and could lead to significant disease remission of SAPHO syndrome. • No significant differences were observed between the two dose groups under the current sample size. • TwHF should be considered for the treatment of osteoarticular lesions in SAPHO syndrome in clinical practice because of significant efficacy, reliable safety, and high socioeconomic value.

Orofacial manifestations of SAPHO syndrome: a systematic review of case reports

SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome is a poorly known disease with cutaneous and osteo-articular manifestations requiring a multidisciplinary care. The aim of this study was to review the case reports that have described oral manifestations in patients suffering for this syndrome. A systematic review of case reports was performed on PubMed and Science Direct on January 2020 among all the articles dealing with the disease. In vitro, preclinical, and clinical studies have not been included to select only the case reports. Eighteen articles, published between 1999 and 2019, were included. All the patients presented mandibular osteomyelitis or sclerosis, associated with various other symptoms such as trismus, temporomandibular joint arthritis, or dysphagia. The data highlight the high variability in the disease's manifestations between people and also in the treatments applied. Knowing the orofacial signs of the SAPHO syndrome, the dental surgeon has a crucial role in the diagnosis procedure and must take place in the multidisciplinary medical team involved in the patient following. Some care adaptations are needed for oral interventions in these patients, depending on their treatments and their handicap. Key Points • Orofacial manifestations of SAPHO syndrome mainly occur on the mandible. • In cases of mandible sclerosis, decorticalization surgeries may be performed. • Oral care are encouraged, especially the preventive treatments to limit the necessity of surgeries. • The complexity in the management of patients suffering for a SAPHO syndrome concerns the oral manifestations, the patient general health and the treatments he has to take every day.

The Diagnosis and Treatment of Adult Patients with SAPHO Syndrome: Controversies Revealed in a Multidisciplinary International Survey of Physicians

INTRODUCTION

This study aimed to investigate the current practice in the diagnosis and treatment of SAPHO syndrome among the international rheumatology and dermatology communities.

METHODS

We conducted an electronic survey among the members of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA), the Japan Spondyloarthritis, and Israeli Societies of Rheumatology.

RESULTS

A total of 78 physicians participated in the survey: rheumatologists (83%, n = 65), dermatologists (11.5%, n = 9), and orthopedics (3.8%, n = 3). SAPHO was considered a subtype of spondyloarthritis by 48.7% (n = 38), a subtype of psoriatic arthritis by 19.2% (n = 15), a separate entity by 25.6% (n = 20), and a subtype of reactive arthritis by 6.4% (n = 5). Palmoplantar pustulosis was the most prevalent cutaneous manifestation (n = 44, 56.4%) and anterior chest pain-the most prevalent osteoarticular manifestation (n = 66, 84.6%). The majority (84.6%, n = 66) voted for the update of the present diagnostic criteria by Khan 1994. Magnetic resonance imaging was considered the preferred imaging modality for the diagnosis of SAPHO by 41% (n = 32). Conduction of bone biopsy for diagnosis of non-infectious osteitis was supported only by 10.3% (n = 8). Patient-reported outcomes were considered the most appropriate measure for the assessment of disease activity by 47.4% (n = 37). The treatment approach was overall similar among the rheumatology and dermatology communities, including non-steroidal anti-inflammatory drugs, bisphosphonates, conventional disease-modifying anti-inflammatory drugs, and biologics.

CONCLUSIONS

Our study underlines the controversy on diagnosis and treatment of SAPHO syndrome among specialists in rheumatology and dermatology and emphasizes an unmet need for update and validation of diagnostic criteria and treatment approach.

Anterior chest wall in SAPHO syndrome: magnetic resonance imaging findings

BACKGROUND

The anterior chest wall (ACW) involvement is characteristic of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome, yet little research has focused on its magnetic resonance imaging (MRI) findings.

PURPOSE

To characterize the MRI features of the ACW in patients with SAPHO syndrome.

METHODS

Seventy-one patients with SAPHO syndrome and ACW involvement evidenced by bone scintigraphy were recruited in this cross-sectional study. The ACW region was scanned using sagittal, axial, and oblique coronal Dixon T2-weighted sequences and axial Dixon T1-weighted sequences. The characteristics of both active inflammatory and chronic structural lesions were evaluated.

RESULTS

The ACW lesions exhibited an asymmetrical distribution and a predilection for the sternocostoclavicular region (93.0%). Notably, 91.5% of the patients had lesions in the area of the anterior first ribs. Bone marrow edema (BME) was observed in 63 (88.7%) patients, which mainly affected the sternocostal joints (87.3%) and the manubrium sterni (84.5%). All of the BMEs were distributed under the articular surface or the bone cortex, consistent with the distribution of the ligaments and joint capsules. Synovitis was detected in 64 (90.1%) patients, with a predilection for the sternoclavicular joints (76.1%). A soft tissue mass or infiltration was found in all the patients who had bone marrow edema. Thirteen (18.3%) patients showed venous stenosis. Structural changes included bone bridge formation (80.3%), hyperostosis (43.7%), and fat infiltration (39.4%). Four common patterns of involvement were observed: the first rib area, the sternoclavicular area, the sternal angle area, and the areas of the second to sixth sternocostal joints.

CONCLUSION

The ACW lesions of SAPHO syndrome demonstrated a triad of enthesitis, synovitis, and osteitis, suggesting complex interactions among the ligaments, synovium, and bones in the region. The inflammatory changes in the first rib area were highlighted in SAPHO syndrome.

Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis (SAPHO): An Interesting Clinical Syndrome

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare disorder that classically involves the musculoskeletal system, i.e. bone, joint and skin. The exact pathogenesis of this syndrome is unknown. However, autoimmunity, infections, immune malfunction and genetic factors are attributed to its pathophysiology. Bone and joint involvements are the hallmark of SAPHO syndrome and not necessarily require cutaneous involvement at the time of diagnosis. X-ray of the affected joints could show osteitis with sclerosis. Anterior chest wall involvement particularly ''bullhead appearance'' seen on bone scan is a striking feature of the syndrome. Erythrocyte sedimentation rate (ESR) is usually elevated amongst the majority of patients. Diagnosis of SAPHO is always challenging and often delayed because of a multitude of symptoms. The mainstay of treatment is control of pain and inflammation with both non-steroidal anti-inflammatory drugs (NSAIDs) and rescue courses of systemic steroids. If failed to control symptoms with first-line agents and in those with severe disease, disease-modifying anti-inflammatory drugs (DMARDs) may be needed eventually. Despite a chronic inflammatory condition, it remains stable in the majority of cases. Here in this case report, we reiterate the importance of early recognition, timely diagnosis and prompt treatment initiation.

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.

Three patterns of osteoarticular involvement in SAPHO syndrome: a cluster analysis based on whole body bone scintigraphy of 157 patients

OBJECTIVES

To explore the patterns of osteoarticular involvement in SAPHO syndrome.

METHODS

Baseline clinical characteristics and imaging data of 99mTc-MDP whole-body bone scintigraphy (WBBS) were collected from 157 out of 164 patients diagnosed with SAPHO syndrome. The twelve most frequently involved osteoarticular sites were analysed by hierarchical cluster analysis with the Ward minimum-variance method.

RESULTS

Three distinctive patterns of osteoarticular involvement were identified: the spinal type (70 patients, 44.6%), with predominantly thoracic, lumbar or sacral vertebral lesions; the costal type (52 patients, 33.1%), with lesions of anterior ribs, particularly the first ribs; and the sternoclavicular type (35 patients, 22.3%), with predominantly sternal and bilateral sternoclavicular lesions, characterized by the typical bullhead sign. Notably, a total of 77 (49%) patients exhibited lesions of ribs on WBBS, of which 61.3% involved the first ribs. Interestingly, patients of spinal type were older at onset of cutaneous manifestations than those of sternoclavicular type (P = 0.036) and costal type (P = 0.035). The disease course was remarkably longer in sternoclavicular type than costal type (P = 0.001) and spinal type (P < 0.001).

CONCLUSION

The osteoarticular involvement in SAPHO syndrome can be categorized as three distinct patterns with different corresponding clinical features. The costal involvement in SAPHO syndrome, which was under-recognized previously, may define a distinct sub-type of the disease.

SAPHO Syndrome Involving the Mandible Treated With 99Tc-MDP

SAPHO (synovitis-acne-pustulosis-hyperostosis-osteitis) syndrome is a chronic inflammatory disease involving multiple organs such as skin and bones. At present, its etiology and pathogenesis are still unclear. Due to the variety of clinical manifestations and the small number of SAPHO syndrome involving the mandible, accurate diagnosis is difficult for oral and maxillofacial surgeons. Here, the authors report that a male patient with SAPHO syndrome involving the maxillofacial skin and mandible, followed for 3 years. We used Tc-MDP (technetium-99 conjugated with methylene disphosphonate) (commercially known as Yunke) to treat this disease and achieved significant clinical treatment. This suggests that Tc-MDP can be used as a bisphosphonate to treat SAPHO syndrome.

A retrospective study of bone scintigraphy in the follow-up of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: is it useful to repeat bone scintigraphy for disease assessment?

OBJECTIVES

To investigate the value of repeated bone scintigraphy in the follow-up of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome and to characterize the changing pattern of osteoarticular lesions revealed by bone scintigraphy.

METHOD

Twenty-four patients with SAPHO syndrome who had repetitively undergone bone scintigraphy and tests of inflammatory markers (erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP)) were included in this retrospective study. The change in accumulation number was recorded as the difference in the number of accumulation sites between consecutive bone scintigraphy. The visual analog scale (VAS) for pain and medications prescribed were also reviewed. The relationships of the change in accumulation number with medication prescribed and change in ESR or CRP were analyzed.

RESULTS

Twenty-four and 23 patients had follow-up tests of ESR and CRP, from which 30 and 28 follow-up data were obtained, containing the corresponding changes in ESR and CRP, respectively. A decrease in total accumulation number observed by bone scintigraphy was rarely observed, while decreases in ESR, CRP, and VAS were predominant. The accumulation number had significantly increased over time (follow-up with ESR: r = 0.389, p = 0.034; follow-up with CRP: r = 0.438, p = 0.020), in accordance with an "imprinting" pattern, while the inflammatory markers and VAS for pain predominantly decreased. There was no significant association between the change in accumulation number (local/total) and the change in ESR or CRP values (p > 0.05) or medications used for SAPHO (p > 0.05).

CONCLUSIONS

This retrospective cohort study of 24 SAPHO patients demonstrated an "imprinting" pattern on bone scintigraphy, without a correlation to the decrease in inflammatory markers, patient disease assessment, or treatment type. Thus, repeated bone scintigraphy did not contribute an additional clinical value for the follow-up of patients with SAPHO.Key Points• In a cohort of 24 SAPHO patients, repeated bone scintigraphy revealed a continuous increase in tracer accumulation number, indicating an "imprinting" pattern.• The change in tracer accumulation number, defined as the difference in the number of accumulation sites between consecutive bone scintigraphy measurements, was inconsistent with the change in ESR, CRP, or VAS for pain.• The medications prescribed for SAPHO did not seem to contribute to a decrease in accumulation number.• Repeated bone scintigraphy did not seem to be useful for the assessment of disease activity in patients with SAPHO.

Long-term remarkable remission of SAPHO syndrome in response to short-term systemic corticosteroids treatment in an immunoglobulin E elevated patient: A case report

RATIONALE

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare auto-inflammatory disease with no standardized treatment. Systemic corticosteroids are only transiently effective, but long-term use would bring complications and would not bring long-term remission. Bone scintigraphy is a first-line method for systematic evaluation of osteoarticular lesions but seems to show an "imprinting" pattern.

PATIENT CONCERNS

A 31-year-old female patient presented significant palmoplantar pustulosis and nail lesion as well as typical tracer accumulation feature on bone scintigraphy with normal hypersensitivity C-reactive protein and erythrocyte sedimentation rate, but an elevated serum immunoglobulin E level.

DIAGNOSIS

The diagnosis was made by dermatological manifestations and classical sign in bone scintigraphy in accordance with the diagnostic criteria proposed in 1988.

INTERVENTIONS

Methylprednisolone was given with a primary dose of 40 mg/day for 1 week followed with a subsequent 20 mg/day oral prednisone for another 1 week and then reduced in a rate of 5 mg/week until the eventual cessation.

OUTCOMES

Long-term remarkable remission on clinical manifestations, MRI performance, and quantitative analysis of bone scintigraphy was achieved.

LESSONS

Identification of specific subtype of SAPHO patient according to skin and nail manifestations as well as immunoglobulin E level may guide the selection of short-term systemic corticosteroids strategy, leading to remarkable long-term remission. Besides, the lesions on bone scintigraphy can hardly disappear in SAPHO patients, and instead, the quantitative analysis of bone scintigraphy and MRI performances may better reflect the change of disease condition and serve as indicator for treatment efficiency.

Oral care of a patient with a SAPHO syndrome and a nickel allergy

SAPHO is an acronym for Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis. The syndrome is difficult to diagnose because it may present many different manifestations in adults and children. Its origin is still unknown, although some infectious, genetic and immune hypotheses have been put forward. We report the case of a 49-year-old woman with SAPHO syndrome, who developed a serious cutaneous allergy following the insertion of a removable partial denture (RPD). The oral care and treatment of this patient are described.

Pediatric Musculoskeletal Imaging: The Indications for and Applications of PET/Computed Tomography

The use of PET/computed tomography (CT) for the evaluation and management of children, adolescents, and young adults continues to expand. The principal tracer used is 18F-fluorodeoxyglucose and the principal indication is oncology, particularly musculoskeletal neoplasms. The purpose of this article is to review the common applications of PET/CT for imaging of musculoskeletal issues in pediatrics and to introduce the use of PET/CT for nononcologic issues, such as infectious/inflammatory disorders, and review the use of 18F-sodium fluoride in trauma and sports-related injuries.

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.

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.

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.

Nuclear Medicine Imaging in Pediatric Infection or Chronic Inflammatory Diseases

In this review article, we focus on the most recent applications of nuclear medicine techniques (mainly ^99mTc/¹¹¹In white blood cells (WBC) scan, [¹⁸F]-FDG-PET/CT, [¹⁸F]-FDG-PET/MRI, and ^99mTc-IL-2 scintigraphy) in the study of children affected by peripheral bone osteomyelitis, fungal infections, inflammatory bowel diseases, and type 1 diabetes, owing to recent important published evidences of their role in the management of these diseases. For osteomyelitis in children, both bone scintigraphy and [¹⁸F]-FDG-PET have a major advantage of assessing the whole body in one imaging session to confirm or exclude multifocal involvement, whereas WBC scan has a limited role. In children with fungal infections, [¹⁸F]-FDG-PET can help in defining the best location for biopsy and can help in evaluating the extent of the infection and organs involved (also sites that were not yet clinically apparent), although its main role is for therapy monitoring. In inflammatory bowel diseases, and Crohn disease in particular, WBC scan has been successfully used for many years, but it is now used only in case of doubtful magnetic resonance (MR) or when MR cannot be performed and endoscopy is inconclusive. By contrast, there is an accumulating evidence of the role of [¹⁸F]-FDG-PET in management of children with Crohn disease, and PET/MR could be a versatile and innovative hybrid imaging technique that combines the metabolic information of PET with the high soft tissue resolution of MR, particularly for distinguishing fibrotic from active strictures. Finally, there are several new radiopharmaceuticals that specifically target inflammatory cells involved in the pathogenesis of insulitis aiming at developing new specific immunotherapies and to select children candidates to these treatments for improving their quality of life.