Evaluation of Gastrointestinal System Complaints and Comorbidities in Pediatric Familial Mediterranean Fever Patients.

OBJECTIVE: Familial Mediterranean fever (FMF) is the most prevalent hereditary autoinflammatory disease among children. Abdominal pain and various gastrointestinal system (GIS) manifestations may arise directly from FMF or concomitantly with FMF. This study aimed to evaluate GIS complaints and findings other than classic peritonitis attacks in patients with FMF and to interpret concomitant GIS and hepatic disorders in these patients. METHODS: The medical and genetic findings of patients with FMF who attended our clinic between December 2011 and December 2021 were reviewed. Gastrointestinal system symptoms, liver function tests, abdominal images, and endoscopic and histopathological data were extracted from medical records. RESULTS: A total of 576 pediatric patients (female, 52.3%) diagnosed with FMF were included. Among them, almost one-fifth displayed GIS complaints, such as abdominal pain, defecation problems, and dyspepsia, distinct from typical FMF attacks. High serum aminotransferase levels were detected in 18.4% of the patients, with viral infections being the most common cause of moderate/severe hypertransaminasemia. In addition, during follow-up, 26.9% of them were referred to the pediatric gastroenterology department. At least 1 gastroenterological and hepatobiliary disorder was detected in 17.5% of the patients because of organic and functional GIS disorders or hepatobiliary disorders, such as gastroesophageal reflux disease, esophagitis, functional dyspepsia, and inflammatory bowel diseases. CONCLUSION: Various GIS and hepatic disorders can be encountered in children with FMF. The spectrum of these complaints and pathologies can range from frequently observed health problems to more severe diseases.

Erysipelas-Like Erythema: A Manifestation of Severe Disease Phenotype in Pediatric Patients with Familial Mediterranean Fever.

OBJECTIVE: Erysipelas-like erythema is the pathognomonic skin manifestation of familial Mediterranean fever although not frequently seen in the pediatric population. This study aims to describe the differences between patients presenting with and without erysipelas-like erythema and to examine the relation of erysipelas-like erythema with subclinical inflammation in a large pediatric cohort of familial Mediterranean fever patients. MATERIALS AND METHODS: This retrospective study from a single pediatric rheumatology referral center included familial Mediterranean fever patients with a follow-up for at least 6 months in the last 5 years. Patients were grouped according to the presence of erysipelas-like erythema and subclinical inflammation. RESULTS: Among 515 patients with familial Mediterranean fever, 35 patients (6.8%) were found to present with erysipelas-like erythema, and the earliest age for erysipelas-like erythema was 2.9 years. All erysipelas-like erythema lesions were defined on lower extremities with concurrent arthritis in 21 patients (60.0%). Compared to other patients in the cohort, patients presented with erysipelas-like erythema had significantly higher frequencies of acute arthritis, subclinical inflammation, and biallelic exon 10 mutations, and they used significantly higher doses of colchicine at the latest visits (all P ≤ .002). Patients with subclinical inflammation more frequently presented with erysipelas-like erythema compared to others without subclinical inflammation (21.7% vs. 2.9%, P < .001). CONCLUSION: Erysipelas-like erythema is an uncommon but important finding that can be a sign of severe disease course and subclinical inflammation in the pediatric population with familial Mediterranean fever.

The Characteristics of Pediatric Patients with Familial Mediterranean Fever Treated with Anti-Interleukin-1 Treatment.

OBJECTIVE: Interleukin-1 inhibitors are effective agents used in colchicine resistance or intoler- ance during the treatment of familial Mediterranean fever. This study aims to review the char- acteristics of patients treated with interleukin-1 inhibitors and their long-term follow-up in a large pediatric cohort of familial Mediterranean fever patients. MATERIALS AND METHODS: The study was conducted in a pediatric rheumatology reference cen- ter. The patients treated with interleukin-1 inhibitors for at least 6 months were included and compared to other patients with familial Mediterranean fever. Clinical and laboratory charac- teristics of the cohort were recorded. RESULTS: Among 542 patients with familial Mediterranean fever, 6.1% (n = 33) were treated with interleukin-1 inhibitors. Colchicine resistance was the reason in 82.8% and renal amyloidosis in 17.2% of the patients. Patients with interleukin-1 inhibitors had earlier disease onset and higher frequencies of acute arthritis, chest pain, and erysipelas-like erythema with pathogenic exon 10 mutations of the MEFV gene (all P < .04). All patients diagnosed with renal amyloidosis also received interleukin-1 inhibitors. Six patients were switched from anakinra to canakinumab or vice versa to control ongoing disease activity. Attack frequency was reduced in all patients. CONCLUSION: Interleukin-1 inhibitors are used in a relatively small number of pediatric patients with familial Mediterranean fever. Patients presenting with earlier disease onset, acute arthri- tis, chest pain, and erysipelas-like erythema and carrying pathogenic exon 10 mutations of the MEFV gene may show a higher need for interleukin-1 inhibitors. In pediatric familial Mediterranean fever patients who are resistant to colchicine, interleukin-1 inhibitors seem to be highly effective agents.

The expanded spectrum of arthritis in children with familial Mediterranean fever.

INTRODUCTION: Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease that can present with various forms of arthritis. This retrospective study aims to evaluate the characteristics of patients with arthritis in a large pediatric cohort of FMF patients. METHODS: The demographic and clinical data were extracted from electronic medical records. Patients with arthritis were grouped as arthritis of FMF and arthritis of FMF-associated diseases. RESULTS: A total of 541 patients were followed with a diagnosis of FMF in the last 5 years. Acute arthritis of FMF (n: 138) was the most common cause. It showed a recurrent course in the majority with a longer duration than other attack symptoms. Significantly higher frequencies of biallelic exon 10 and M694V mutations, erysipelas-like erythema, and protracted febrile myalgia were detected in these patients, particularly in those older than 2 years of age. Sacroiliitis of FMF was the second most common cause (n: 19). Patients with acute arthritis and sacroiliitis of FMF needed higher doses of colchicine. One patient with neonatal-onset FMF and M694V homozygosity was diagnosed with protracted arthritis. Arthritides of FMF-associated diseases including IgA vasculitis (n: 10), juvenile idiopathic arthritis (n: 9), chronic nonbacterial osteomyelitis (n: 5), and inflammatory bowel disease (n: 2) were detected in 26 patients. CONCLUSIONS: Arthritis is an important clinical finding of FMF mostly associated with M694V mutations. The frequency of protracted arthritis is declined, whereas sacroiliitis of FMF and arthritis of associated diseases expand the spectrum of arthritis. This study represents the changing face and current perspectives of arthritis in FMF. Key Points • Arthritis is an important clinical finding of familial Mediterranean fever (FMF) that can present in various forms • Arthritis is most likely associated with M694V mutations • The frequency of protracted arthritis is declined whereas sacroiliitis of FMF and arthritis of associated diseases expand the spectrum of arthritis in FMF.

Nutcracker syndrome: a potentially underdiagnosed cause of proteinuria in children with familial Mediterranean fever.

INTRODUCTION: Familial Mediterranean fever (FMF) is the most common hereditary autoinflammatory disease with an increased risk for secondary amyloidosis. Since lifelong colchicine has been the treatment of choice that prevents renal amyloidosis, non-amyloid kidney diseases are more frequently considered in the differential diagnosis of proteinuria. Nutcracker syndrome (NCS) can be one of the confounding causes. This long-term retrospective study aimed to evaluate the causes of proteinuria in a pediatric cohort of patients with FMF and discuss changing trends in recent years . METHODS: Demographic, clinic, and laboratory data were extracted from electronic medical records of patients with FMF. All urine tests of the study population were reviewed. Patients were evaluated for persistent proteinuria and grouped according to the etiology of proteinuria. RESULTS: A total of 576 patients with FMF were identified with a mean follow-up of 6.3 years in the last 10 years; 8% had persistent proteinuria. The etiology was NCS in 67.5% of the patients with proteinuria, and renal amyloidosis was less commonly encountered (15%) without any new diagnosis for the last 8 years. Non-amyloid kidney diseases were also diagnosed in 17.5% of the patients. Patients with NCS had significantly lower BMI than other patients in the cohort and less subclinical inflammation, higher hemoglobin concentration, and milder levels of proteinuria with normal serum albumin and eGFR than other patients with proteinuria. CONCLUSION: Nutcracker syndrome is the leading cause of proteinuria in children with FMF nowadays, and it should be kept in mind during the evaluation of proteinuria in these patients. A higher resolution version of the Graphical abstract is available as Supplementary information.