The relation between C-reactive protein and serum amyloid A in patients with autoinflammatory diseases.

BACKGROUND: Autoinflammatory diseases are rare disorders of the innate immune system characterized by fever and other signs of inflammation. A feared complication of autoinflammatory diseases is the development of AA amyloidosis. AA amyloidosis is caused by extracellular deposition of soluble serum amyloid A (SAA) proteins as insoluble amyloid fibrils leading to organ damage. Prolonged high levels of SAA are a prerequisite to develop AA amyloidosis. Since measurement of SAA is relatively expensive and sometimes unavailable, C-reactive protein (CRP) is often used as a surrogacy marker to test for inflammation. OBJECTIVE: The aim of this research is to evaluate the possible relation between CRP and SAA. METHODS: A retrospective cohort of patients with autoinflammatory diseases (n = 99) where SAA and CRP blood testing was performed in the period between 2015 and 2021 in the University Medical Centre in Groningen was used to investigate the correlation between CRP and SAA. RESULTS: CRP and SAA have a high correlation (rho = 0.755, p < 0.001). A CRP value below 0.45 mg/L results in 100% sensitivity for SAA below 4 mg/L. CRP below 5 mg/L is a good predictor of SAA below 4 mg/L with 85.4% sensitivity and 83.6% specificity. Only prednisone and erythrocyte sedimentation rate (ESR) significantly influence the relation between CRP and log10SAA. CONCLUSION: There was a significant correlation between CRP and SAA in our retrospective cohort. CRP levels below 5 mg/L proved to be highly predictive of SAA levels below 4 mg/L. This may not be true for patients on steroids.

Role of FDG-PET/CT in children with fever of unknown origin.

PURPOSE: To determine the role of 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET)/computed tomography (CT) in children with fever of unknown origin (FUO). METHODS: This retrospective single-center study included 110 children (0-18 years) with FUO who underwent FDG-PET/CT between 2010 and 2019. The diagnostic value of FDG-PET/CT for identifying cause of fever was calculated, treatment modifications after FDG-PET/CT were assessed, and logistic regression analyses were performed to identify clinical and biochemical factors associated with FDG-PET/CT outcome. RESULTS: In 53 out of 110 patients (48%), FDG-PET/CT identified a (true positive) cause of fever. Endocarditis (11%), systemic juvenile idiopathic arthritis (5%), and inflammatory bowel disorder (5%) were the most common causes of FUO. In 42 patients (38%), no cause of fever was found on FDG-PET/CT. In 58 out of 110 patients (53%), treatment modifications were made after FDG-PET/CT. FDG-PET/CT achieved a sensitivity of 85.5%, specificity of 79.2%, positive predictive value of 84.1%, and negative predictive value of 80.9%. On multivariate logistic regression, C-reactive protein was positively associated with finding a true positive focus of fever on FDG-PET/CT (OR = 1.01 (95% CI 1.00-1.02) per mg/L increase in CRP), while leukocyte count was negatively associated with finding a true positive focus of fever (OR = 0.91 (95% CI 0.85-0.97) per 109 leukocytes/L increase). CONCLUSION: FDG-PET/CT is a valuable diagnostic tool in the evaluation of children with FUO, since it may detect a true underlying cause in almost half (48%) of all cases where none was found otherwise. It allows full-body evaluation in patients without disease-specific symptoms on one examination. CRP and leukocyte count were significantly associated with FDG-PET/CT results, which may contribute to a priori assessment on the outcome of FDG-PET/CT. Future research could be aimed at evaluating more patient-specific factors to prospectively estimate the added value of FDG-PET/CT in children with FUO.

[A cavernous haemangioma of the colon as the cause of rectal bleeding in childhood]. / Een caverneus hemangioom van het colon als oorzaak van rectaal bloedverlies op de kinderleeftijd.

A 13-year-old girl presented with rectal bleeding, abdominal pain and a palpable mass in the lower right abdomen. The history mentioned a chronic anaemia since she was 2 years old. Further examination did not give any indications for inflammation as etiological factor and showed a thickening of (apparently) the small intestine. A laparotomy was performed, since the age and presentation made a malignant lymphoma a probable diagnosis. The combination of chronic anaemia and rectal bleeding also suggested a benign vascular malformation. A large cavernous haemangioma of the transverse colon was found. This was resected and the patient fully recovered. Although a haemangioma of the colon is rare, it is important to keep this possibility in mind in the case of rectal bleeding in childhood, especially when other causes of rectal bleeding are excluded. Usually haemangiomas show spontaneous regression, but this is rare in intestinal haemangiomas. Surgical resection is the therapy of choice in the case of a solitary haemangioma.