SAPHO syndrome: is a range of pathogen-associated rheumatic diseases extended?

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.

Sexual function assessment in patients with SAPHO syndrome: a cross-sectional study

INTRODUCTION

SAPHO syndrome is a group of special syndromes characterized by synovitis, acne, pustulosis, hyperostosis and osteitis. Skin lesions and joint damage are the main clinical manifestations. Among them, females mostly present with palm toe pustulosis, while males have severe acne as the main external manifestation. The bone and joint damage characterized by bone hypertrophy and osteitis is the core manifestation of SAPHO and affects all parts of the body. SAPHO syndrome causes great physical and mental suffering to patients, and it also brings a huge financial burden to the family. The purpose of this study is to explore the impact of SAPHO on the quality of sexual life of patients.

METHODS

We screened and included 249 SAPHO patients (169 women and 80 men) from Peking Union Medical College Hospital (Beijing, China). First, we recorded the basic situation of the patient through questionnaires (including gender, age, SAPHO duration, BMI, smoking, drinking, marital status, educational level, occupational status and work status.). Then, the patient needed to fill in the Short Form-36 quality of life questionnaire (SF-36 QoL) to record the quality of life. For Sexual dysfunction (SD), female patients needed to fill in the Female Sexual Function Index (FSFI) to assess the quality of sexual life; while the International Index of Erectile Function (IIEF) was used to assess the SD of male patients. At the same time, we used self-esteem and relationship questionnaire (SEAR) to analyze the psychological state of SAPHO patients. Finally, we performed statistical analysis on the data obtained, and then explored the connection between SAPHO and SD.

RESULTS

In this cross-sectional study, a total of 249 patients completed the questionnaire and constituted the study population. We found that among 169 female patients, 124 patients had FSD (73.4%); while 45 patients did not have FSD (26.6%); and among 80 male patients, 45 (56.3%) had ED; However, 35 patients did not have ED (43.7%). The results of the quality of life and mental state assessment showed that female patients with SD showed lower scores in terms of mental state. Among all male participants, we found no significant difference in quality of life and mental state among participants with or without SD. In addition, there was no significant difference in the duration of SAPHO between female and male participants with or without SD.

CONCLUSION

This study is the first to evaluate the SD of SAPHO patients. The incidence of SD in female SAPHO patients is higher than that in male patients; the cause of female SD may be mainly psychological factors. These results prove that it is particularly important to focus on regulating their psychological state while diagnosing and treating SAPHO patients in clinical practice.

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.

Beyond the Acne

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) is a relatively rare and often underdiagnosed disorder characterized by chronic inflammation affecting the bones, joints, and skin. While the precise cause of SAPHO syndrome remains elusive, multiple factors such as genetics, immunological dysregulation, and bacterial influences have been implicated in its pathogenesis. One notable aspect of SAPHO syndrome is the wide variability of symptoms experienced by afflicted individuals. A diverse array of osteoarticular manifestations may be observed, with common sites of involvement including the anterior chest wall, sacroiliac joints, and peripheral joints. Concurrently, patients often present with various skin disorders, such as palmoplantar pustulosis or acne, further adding to the complexity of the syndrome's clinical presentation. Treatment strategies for SAPHO syndrome primarily focus on managing symptoms and improving the quality of life for affected individuals. Nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, methotrexate (MTX), and tumor necrosis factor (TNF) inhibitors are considered to modulate the immune response and provide relief. One of the challenges encountered in diagnosing SAPHO syndrome is its potential overlap with other related conditions, leading to diagnostic confusion and difficulties. Distinguishing SAPHO syndrome from similar entities can be complex, requiring a comprehensive evaluation of clinical features, imaging studies, and laboratory investigations. We would like to share an intriguing case involving a 28-year-old woman who arrived with perplexing symptoms of pain in her bilateral hands and feet, her lower back, and acne in the bilateral upper arms and thighs. Through a comprehensive workup, the underlying SAPHO syndrome was uncovered, and it was effectively managed using adalimumab.

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.

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.

Long-term Clinical Outcomes in Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis Syndrome

Objective

To assess the outcome of empirical therapeutic interventions for synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome.

Methods

The clinical features and treatment outcomes of a cohort of 21 patients diagnosed with SAPHO in Western Australia were reviewed retrospectively.

Results

All 21 patients met published diagnostic criteria; 20 (95%) were Caucasian, and the median age was 47 years. The median follow-up was 6 years (range, 2 to 32 years). Three patients (14%) received no treatment; 18 (86%) required conventional synthetic disease-modifying antirheumatic drug (DMARDs). Thirteen (62%) had an initial good response to methotrexate; 8 relapsed and progressed to biologic DMARDs (bDMARDs) during a period of 14 years. Of the 13 recipients on a tumor necrosis factor inhibitor, 11 (85%) continued treatment for a median of 4 years (range, 1 to 14 years), whereas none of 3 recipients of interleukin 17/23 continued treatment (median, 4 months). Higher Physician Global Assessment scores (better outcomes) were observed in bDMARD recipients (mean, 7.06±2.24 [SD]) compared with non-bDMARD recipients (mean, 5.63±2.50; P=.1672) after a median of 3 years of therapy.

Conclusion

This study describes the broad range of clinical manifestations in SAPHO, variable courses over time, and inconsistent outcomes with diverse empirical therapies. Moderately good long-term treatment outcomes were observed in most recipients of tumor necrosis factor inhibitor. Poorer outcomes were observed with bisphosphonates and interleukin 17/23 axis inhibitors; however, low numbers preclude robust comparison. Suboptimal treatment may be associated with poorer clinical outcomes and greater skeletal damage.

Trial Registration

Australian and New Zealand Clinical Trials Registry: ACTRN12619000445178

Chronic Nonbacterial Osteomyelitis of the Sternocostoclavicular Region in Adults: A Single-Center Dutch Cohort Study

Sternocostoclavicular hyperostosis (SCCH) is a rare autoinflammatory bone disorder caused by chronic nonbacterial osteomyelitis (CNO), which is associated with sclerosis and hyperostosis primarily affecting the sternum, the medial end of the clavicles, and the first ribs. Other areas of the axial skeleton may also be affected. The more severe synovitis–acne–pustulosis–hyperostosis–osteitis (SAPHO) syndrome is additionally associated with dermatoses and joint manifestations. This Dutch retrospective cross‐sectional single‐center cohort study characterizes the spectrum of clinical features in adult CNO/SCCH patients at the time of diagnosis. The only inclusion criteria was the availability of complete sets of clinical and imaging data systematically collected over three decades using in‐house protocols. Data from 213 predominantly female patients (88%) with a median age of 36 years at presentation were studied. The mean diagnostic delay was 5 ± 5 years. The main symptoms were chronic pain (92%), bony swelling (61%), and restricted shoulder girdle function (46%); 32% had palmoplantar pustulosis and 22% had autoimmune disease. The majority (73%) had isolated SCCH; 59 (27%) had additional localizations in vertebrae (19%), the mandible (9%), or both (2%); 4 had SAPHO. The prevalence of current or past smoking was high (58%), particularly for patients with palmoplantar pustulosis (76%). There was a significant relationship between delay in diagnosis and both the extent of affected skeletal sites (p = 0.036) and erythrocyte sedimentation rate levels (p = 0.023). Adult‐onset CNO is characterized by distinctive clinical and radiological features, but diverse aspects of its spectrum are currently not fully captured by a comprehensive classification. Delayed diagnosis is still common and potentially associated with irreversible structural changes and debilitating chronic symptoms, increasing the burden of illness and negatively impacting on quality of life. It is hoped that findings from this study will dispel confusion about nomenclature and classification of adult‐onset CNO and increase awareness of its distinctive clinical and radiological features, and thus facilitate early diagnosis and referral for treatment, which should positively impact prognosis by preventing disease progression, although this remains to be established. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

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.

A patient with chronic sacroiliitis undiagnosed for three years after isotretinoin use

Background

Isotretinoin (ISO) is a synthetic vitamin A derivative which has been used for treatment-resistant acne vulgaris. Although most musculoskeletal side effects of ISO are common, including myalgia, arthralgia, and back pain, sacroiliitis is one of the uncommon side effects. ISO-induced sacroiliitis usually completely resolves within a few months by the cessation of the drug.

Case presentation

In this paper, we present a 26-year-old female patient with chronic sacroiliitis that was probably induced by ISO and not resolved by the discontinuation of the drug.

Conclusion

In this patient, sacroiliitis was overlooked for three years. Therefore, ISO usage should be considered in the differential diagnosis of sacroiliitis and low back pain.

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.

Paradoxical skin lesions induced by anti-TNF-α agents in SAPHO syndrome

The objectives of the study were to characterize the clinical picture of paradoxical skin lesions in SAPHO patients treated with anti-TNF-α agents and to explore its pathogenesis. Patients treated with anti-TNF-α therapy were identified from a cohort of 164 SAPHO patients. The clinical data and skin biopsies were collected. The usage, efficacy, and side effects of anti-TNF-α therapy were recorded. Forty-one (25.0%) patients received anti-TNF-α therapy, of which seven (17.1%) developed paradoxical skin lesions after 1 to 14 infusions. Patients with such lesions were older at onset of skin lesions than those without (p = 0.034). Expression of TNF-α in palmoplantar pustulosis increased after anti-TNF-α therapy in the two examined patients with exacerbated skin lesions. Anti-TNF-α therapy induces paradoxical skin lesions in 17.1% SAPHO patients. Late onset of skin manifestations is associated with an increased risk of such lesions. The paradoxical elevation of TNF-α expression in lesions may contribute to this phenomenon.

Etanercept in the treatment of refractory SAPHO syndrome

OBJECTIVE

To explore the application and efficacy of TNF-α inhibitors in the treatment of SAPHO syndrome.

METHODS

Two cases of refractory SAPHO syndrome were successfully treated with etanercept. And pain scores, laboratory parameters and functional index were used to judge the efficacies. Literature was also systemically reviewed.

RESULTS

Both patients achieved marked clinical remission. There was no obvious toxic or adverse response.

CONCLUSION

Etanercept has rapid and definite efficacies in the treatment of patients with refractory SAPHO syndrome.

[SAPHO syndrome]

The SAPHO syndrome, an acronym for synovitis, acne, pustulosis, hyperostosis and osteitis, is a rare disease which affects bones, joints and the skin. The main osteoarticular features are hyperostosis and osteitis. Osteoarticular symptoms predominantly occur on the anterior chest wall but the spine and the peripheral skeleton can also be involved. The most important skin affections are palmoplantar pustulosis and severe acne. The etiology of this syndrome remains unclear but infectious, immunological and genetic factors are involved. The diagnostic features of SAPHO syndrome are clinical and radiological. The most important diagnostic procedure is Tc-99 m bone scintigraphy but conventional x-rays as well as computed tomography (CT) and magnetic resonance imaging (MRI) can also contribute to the final diagnosis. Bone histology and positron emission tomography CT (PET-CT) may help to differentiate SAPHO syndrome from malignancies and infectious osteomyelitis. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the cornerstone of treatment. The results obtained using antibiotics and disease-modifying antirheumatic drugs (DMARDs), such as sulfasalazine and methotrexate are inconsistent. Bisphosphonates and anti-tumor necrosis factor (anti-TNF) drugs have shown promising results in small studies but further research is still necessary.

New discoveries in CRMO: IL-1β, the neutrophil, and the microbiome implicated in disease pathogenesis in Pstpip2-deficient mice

Chronic non-bacterial osteomyelitis (CNO), chronic recurrent multifocal osteomyelitis (CRMO) and synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO) syndrome are autoinflammatory disorder(s) in which sterile osteomyelitis is frequently accompanied by inflammatory conditions of the joints, skin, or intestine. Patients with CRMO commonly have a personal or family history of psoriasis, inflammatory bowel disease, and inflammatory arthritis, suggesting shared disease pathogenesis. Work by our group and others has demonstrated that dysregulation of interleukin-1 (IL-1) signaling can drive sterile osteomyelitis in the two human monogenic forms of the disease. Recent work in the chronic multifocal osteomyelitis (cmo) mouse model demonstrates that the disease is IL-1-mediated, that neutrophils are critical effector cells and that both caspase-1 and caspase-8 play redundant roles in mediating the cleavage of pro-IL-1β into its biologically active form. Recent data in the cmo mouse demonstrate that dietary manipulation alters the cmo microbiome and can prevent the development of osteomyelitis. Further investigation is needed to determine the specific components of the diet that result in protection from disease and if this finding can be translated into a treatment for human CRMO.

The SAPHO syndrome revisited with an emphasis on spinal manifestations

The synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome includes a group of chronic, relapsing, inflammatory musculoskeletal disorders with similar manifestations, in particular synovitis, hyperostosis, and osteitis, which may or may not be associated with neutrophilic skin eruptions such as palmoplantar pustulosis and acne conglobata. The syndrome occurs at any age, can involve any skeletal site, and its imaging appearances are variable, depending on the stage/age of the lesion and imaging method. The diagnosis is difficult if there is no skin disease. Awareness of the imaging appearances, especially in the spine, may help the radiologist in avoiding misdiagnosis (e.g., infection, tumor) and unnecessary invasive procedures, while facilitating early diagnosis and selection of an effective treatment. In this article, we provide an overview of the radiological appearances of SAPHO syndrome, focusing on the magnetic resonance imaging findings of vertebral involvement, and present relevant clinical and pathological features that assist early diagnosis.

Autoinflammatory bone disorders: update on immunologic abnormalities and clues about possible triggers

PURPOSE OF REVIEW

To provide an update on the genetics and immunologic basis of autoinflammatory bone disorders including chronic recurrent multifocal osteomyelitis including the monogenic forms of the disease.

RECENT FINDINGS

Ongoing research in murine, canine and human models of sterile bone inflammation has solidified the hypothesis that sterile bone inflammation can be genetically driven. Mutations in Pstpip2, LPIN2 and IL1RN have been identified in monogenic autoinflammatory bone disorders that have allowed more detailed dissection of the immunologic defects that can produce sterile osteomyelitis. Recent studies in murine chronic multifocal osteomyelitis, deficiency of the interleukin-1 receptor antagonist (DIRA), Majeed syndrome and SAPHO syndrome reveal abnormalities in innate immune system function. IL-1 pathway dysregulation is present in several of these disorders and blocking IL-1 therapeutically has resulted in control of disease in DIRA, Majeed syndrome and in some cases of SAPHO and CRMO. Basic research demonstrates the importance of the innate immune system in disease pathogenesis and offers clues about potential disease triggers.

SUMMARY

Research and clinical data produced over the last several years support the important role of innate immunity in sterile osteomyelitis. Based on what has been learned in the monogenic autoinflammatory bone disorders, IL-1 is emerging as an important pathway in the development of sterile bone inflammation.

Severe inflammation associated with synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome was markedly ameliorated by single use of minocycline

We describe the case of a 63-year-old female who presented with severe inflammatory spondylitis, refractory to various antibiotics. Mycobacterial and fungal osteomyelitis were unlikely. Although asymptomatic, she also had osteomyelitis in the sternocostoclavicular region, and was suspected of having synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome, against which minocycline showed marked efficacy. The presence of severe inflammatory SAPHO, albeit rare, together with the marked efficacy of tetracycline, should be noted.

Diagnosing the SAPHO syndrome: a report of three cases and review of literature

SAPHO, an acronym for synovitis, acne, pustulosis, hyperostosis and osteitis, is a heterogeneous entity with myriad presentations and features overlapping with other entities. It is a differential in patients presenting with skin and bone symptoms, either singly or in combination. Often misdiagnosed radiologically as a malignancy or infection, the diagnosis is seldom thought of. We present three cases referred to us for evaluation of findings unrelated to the presenting symptoms. After evaluation, a (99)Tc bone scan was ordered, which showed the 'bull's head sign' in all the three cases, confirming the diagnosis. We review the literature for SAPHO. It has a few features which point to its diagnosis and can help us to distinguish it from other seronegative arthritis. The clinician should be aware of this entity and should not hesitate to order a (99)Tc bone scan. We conclude that SAPHO is not rare, but rather, it is underdiagnosed. High index of suspicion is necessary for diagnosis. A (99)Tc bone scan is diagnostic and should be ordered in patients having any of the presenting features of the syndrome. We put forward the suggestion of using (99)Tc bone scintigraphy to define a 'pre-MRI' stage of ankylosing spondylitis.

Sacroiliitis secondary to isotretinoin

Reported is the case of a 17-year old male with sacroiliitis confirmed by magnetic resonance imaging (MRI) while undergoing isotretinoin treatment for acne vulgaris. The cessation of isotretinoin and symptomatic treatment resolved the symptoms within 6 weeks, with no signs of sacroiliitis on repeat MRI 10 months later. The temporal association of disease onset and commencement of isotretinoin along with rapid recovery on withdrawal supports the role of isotretinoin in this case.

Propionibacterium acnes: infection beyond the skin

Propionibacterium acnes is a Gram-positive bacterium that forms part of the normal flora of the skin, oral cavity, large intestine, the conjunctiva and the external ear canal. Although primarily recognized for its role in acne, P. acnes is an opportunistic pathogen, causing a range of postoperative and device-related infections. These include infections of the bones and joints, mouth, eye and brain. Device-related infections include those of joint prostheses, shunts and prosthetic heart valves. P. acnes may play a role in other conditions, including inflammation of the prostate leading to cancer, SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome, sarcoidosis and sciatica. If an active role in these conditions is established there are major implications for diagnosis, treatment and protection. Genome sequencing of the organism has provided an insight into the pathogenic potential and virulence of P. acnes.

Tumor Necrosis Factor-α Blockers in SAPHO Syndrome: Table 1

Objective.

To analyze the clinical efficacy of anti-tumor necrosis factor-α (TNF-α) therapy in treatment of synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome, we describe cases of refractory SAPHO syndrome and review cases treated with anti-TNF-α reported in the literature.

Methods.

We describe 6 cases of patients with SAPHO syndrome treated with anti-TNF-α between 2004 and 2008. Therapeutic response was evaluated according to improvement in pain score, amelioration of disease activity, and improvement in function. The efficacy of treatment was considered to be reduced need for analgesics and/or antiinflammatory therapy.

Results.

In our series, 4 patients received infliximab, 1 etanercept, and 1 adalimumab. These treatments brought clinical response in 4 patients (66.6%): response was sustained with infliximab in 1 case for 7 months; with adalimumab in another case for 22 months; and with etanercept in 2 cases for 1 and 42 months, respectively. In contrast, 2 other patients showed no response to infliximab. Improvement was initially temporary after infusions 1 and 2, then pain recurred at Week 14. Skin lesions were healed in 3 of 4 cases, but recurred or worsened in 2 cases, after infusion 2 of infliximab. Treatment was generally well tolerated. Paradoxical psoriasis was noted in 2 cases and urticaria in 1.

Conclusion.

Given our results and those from the literature, TNF-α blockers should be considered in the therapeutic strategy of refractory cases of SAPHO syndrome, despite their effect seeming less impressive than in other spondyloarthropathies.