FDG PET Helpful for Diagnosing SAPHO Syndrome

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.

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.

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.

A case of SAPHO syndrome with destructive spondylodiscitis suspicious of tuberculous spondylitis

We report a rare case of synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome in which the differential diagnosis included tuberculous spondylitis and the patient ultimately required reconstructive spinal surgery. The patient was a 60-year-old woman who presented with severe low-back and leg pain after treatment for tuberculosis. Roentgenography and magnetic resonance imaging of the lumbar spine revealed destructive changes suggestive of tuberculous spondylitis. [(18)F]-fluoro-2-deoxyglucose positron emission tomography/computed tomography showed uptake in the cervical spines, lumbar spines, and sacroiliac joints from which she was suspected of having SAPHO syndrome without skin manifestations. However, as her symptoms did not respond to conservative treatment, we performed reconstructive surgery of the lumbar spine. Spinal specimens obtained surgically showed nonspecific inflammation and fibrous hypertrophy of the bone marrow, confirming a diagnosis of the SAPHO syndrome. Her symptoms improved markedly after surgery, although she required occasional prednisolone for moderate polyarthralgia and leg pain.

Síndrome SAPHO

We report two cases, one 23 and one 27 year old man, with several years background of sternal and sternoclavicular joints pain, respectively. The laboratory tests were normal. Based on the clinical, radiologic and scintigraphic findings, SAPHO syndrome was diagnosed. Bone scintigraphy makes it possible to obtain a whole body scan in a single whole body scan, and can be used for differential diagnosis of other osteoarticular diseases and for evolutive control and therapeutic response.