Characteristics of FDG-PET findings in the diagnosis of systemic juvenile idiopathic arthritis

18F-FDG PET/CT Findings Overlapping Lymphoma in a Patient with Systemic Juvenile Idiopathic Arthritis

Systemic juvenile idiopathic arthritis (sJIA) is an important autoinflammatory disease whose first symptom is usually fever, and life-threatening conditions such as macrophage activation syndrome can develop when diagnosis and treatment is delayed. sJIA is an exclusion diagnosis, and there is no specific test that distinguishes it from other febrile diseases. We report the positron emission tomography/computed tomography (PET/CT) findings of sJIA in a 12-year-old girl who presented with fever, rash, and arthralgia. ¹⁸F-fluorodeoxyglucose (FDG) uptake was observed in the spleen, bone marrow, and lymph nodes in ¹⁸F-FDG PET/CT performed to investigate the etiology of fever of unknown origin. The result of excisional biopsy performed with the suspicion of lymphoma from the left cervical lymph node with intense ¹⁸F-FDG uptake was reported as reactive hyperplasia. PET/CT is an alternative diagnostic method for patients with fever of unknown origin. In this case report, we emphasize that in patients with sJIA, there may be intense fluorodeoxyglucose-avid lymph nodes that may lead to the consideration of lymphoproliferative disease, and PET/CT findings along with spleen and bone marrow involvement may overlap with lymphoma.

Systemic Juvenile Idiopathic Arthritis in two children; case report on clinical course, challenges in diagnosis and the role of FDG‐PET/CT‐scan

Systemic juvenile idiopathic arthritis (sJIA, also called Still's disease) is a rare childhood auto‐inflammatory disease with significant morbidity. This case report illustrates the clinical course and highlights diagnostic challenges. FDG‐PET/CT imaging may be beneficial in the diagnostic process for some cases, in order to achieve rapid diagnosis and early treatment.

Clinical practice guidance for juvenile idiopathic arthritis (JIA) 2018

Juvenile idiopathic arthritis (JIA) is the most common disease in pediatric rheumatism. There is no specific symptom or examination finding for JIA, and the diagnosis is made by exclusion and differentiation. Because non-pediatric rheumatologists are sometimes involved in medical care, 'proposal for JIA guidance on diagnosis and treatment for primary care pediatricians and non-pediatric rheumatologists' was first published in 2007. In these 10 years, a number of new findings on pathophysiology and treatment of JIA have been published; therefore, we propose this guidance of 2018th edition aiming at updating and standardization of JIA medical care in Japan. This edition included the management of uveitis, macrophage activation syndrome, infectious diseases before and during treatment. Moreover, details of biologics are also described. Although this guidance is tailored to adaptation of examinations and drugs, we do not purpose to limit the physicians' discretion in clinical practice. This guidance should be viewed as recommendations and be individualized according to the condition of the patient. We hope that medical care for JIA will advance and more patients will get benefit based on this guidance. Then, further revisions are needed due to changes in future conditions.

FDG-PET in macrophage activation syndrome associated with systemic juvenile idiopathic arthritis

We herein describe a case of systemic juvenile idiopathic arthritis (s-JIA)-associated macrophage activation syndrome (MAS) in which the ^18F fluorodeoxyglucose positron emission tomography (^18F FDG-PET) findings were characteristic. The pattern of greater ^18F FDG accumulation into the spleen compared with the liver was more remarkable in this patient compared with s-JIA. This pattern, however, was also observed in cases of acute leukemia. In the present patient, serum interleukin (IL)-18 was extremely elevated (255 000 pg/mL), whereas in leukemia patients it is mildly elevated (360-1480 pg/mL). ^18F FDG-PET might be a useful indicator of s-JIA and MAS in patients with fever of unknown origin. The pattern of ^18F FDG accumulation, however, can also be observed in acute leukemia. The combination of ^18F FDG-PET and serum IL-18 might be useful for the diagnosis of s-JIA and MAS.