Purpose To assess increased sacroiliac joint (SIJ) uptake on 18 F-NaF PET/CT and to compare with MRI for inflammation and with CT scan for structural damages in a population of 23 patients with spondyloarthritis (SpA). Methods Twenty-three patients with active SpA according to the Assessment of SpondyloArthritis international Society (ASAS) and/or modified NY criteria were included. All patients had a pelvic radiograph, MRI, and CT scan of the SIJ and 18 F-NaF PET/CT examinations within a month, analyzed by three blinded readers. MRIs were assessed according to the ASAS criteria and SPARCC method. On CT scans, erosion and ankylosis were quantified using the same methodology. On the 18 F-NaF PET, abnormal uptake was assessed using a qualitative method inspired by the ASAS criteria and two quantitative approaches (the PET-activity score according to the SPARCC method and Maximum Standardized Uptake Value (SUVmax)). Results Structural sacroiliitis was observed on 7 radiographs and 10 CT scans; 10 MRIs showed inflammatory sacroiliitis, and 20 patients had a positive PET. The inter-reader reliability was good for the PET activity score and good to excellent for the SUVmax. A positive PET was not correlated with a positive MRI or with a structural sacroiliitis on CT scan. The PET-activity score and SUVmax were correlated with the SPARCC inflammation score but not with erosion or ankylosis scores on CT scan. Conclusion Abnormal uptake by the SIJ on 18 F-NaF PET is more frequent than inflammatory and structural sacroiliitis in a population of SpA patients. The PET activity score and SUVmax had good correlations with inflammatory sacroiliitis but not with structural lesions on CT scan.

No abstract

No abstract

BackgroundPrepatellar bursitis is not very frequent in daily practice and the main causes are infections, crystal arthropathies or trauma.We report the case of a 49-year-old man presented to our department with bilateral anterior knee pain. Pain started 3 months ago without any triggering factor. He denied any trauma or infection. The patient also denied any history of gout, rheumatoid arthritis or systemic lupus.ObjectivesOn clinical exam, bilateral knee swellings were noticed consistent with prepatellar bursitis with no wound or abrasion, no fever, signs of arthritis or lymphadenopathy.MethodsKnee ultrasonography and skeletal scintigraphy confirmed symmetrical prepatellar bursitis. Laboratory findings showed elevated ESR and CRP but no other abnormalities.Few days later, the patient presented with subcutaneous painful nodules that appeared on his forearms. Biopsy was done and showed deep subcutaneous sarcoid nodules of Darier-Roussy, confirming the diagnosis of sarcoidosis.Further work up revealed typical sarcoid pulmonary involvement. Bilateral hilar and mediastinal lymphadenopathy with beaded appearance of interlobular septa were noticed on CT-scan of the chest.The Positron Emission Tomography showed abnormally high 18F-fluorodeoxy glucose uptake in the thoracic lymph nodes.ResultsAll the diagnostic work up confirmed the diagnosis of systemic sarcoidosis. The decision was to start oral corticosteroids. Few days after starting the systemic steroids, the skin lesions and the knees pain improved significantly.ConclusionsThe conclusion is that after excluding the main causes of bursitis (infection, trauma and inflammatory arthritis) (1), it's necessary to keep in mind sarcoidosis as possible diagnosis.This clinical observation is important because involvement of the bursa is a rare musculoskeletal manifestation of sarcoidosis (2). Moreover, it's very uncommon to diagnose sarcoidosis presenting with just bilateral prepatellar bursitis with no other musculoskeletal or rheumatological symptoms (3).The association of bursitis, inflammatory skin lesions and thoracic lymphadenopathy is uncommon but may suggest the diagnostic of sarcoidosis.References Mathieu S, Prati C, Bossert M, Toussirot E, Valnet M, Wendling D. Acute prepatellar and olecranon bursitis. Retrospective observational study in 46 patients. Joint Bone Spine. 2011;7:423–4.Fujimoto H, Shimofusa R, Shimoyama K, Nagashima R, Eguchi M. Sarcoidosis presenting as prepatellar bursitis. Skeletal Radiol. 2006;35:58–60.Ruangchaijatuporn T, Chang EY, Chung CB. Solitary subcutaneous sarcoidosis with massive chronic prepatellar bursal involvement. Skeletal Radiol. 2016;45:1741–5. Disclosure of InterestNone declared

No abstract