Thymic carcinoma presenting with overlap polyarthritis and myositis: A rare paraneoplastic syndrome in childhood.

Thymic tumors are very rare neoplasms in children and account for less than 1% of mediastinal tumors in pediatric patients. One-third of the pediatric patients present with symptoms related to the compression of the tumor mass on the surrounding anatomic structures, and paraneoplastic syndromes such as myasthenia gravis, pure red cell aplasia, acquired hypogammaglobulinemia, and connective tissue disorders, which rarely occur in children with thymic tumors. Herein, we report a case of thymic carcinoma mimicking the symptoms of a connective tissue disease with symmetrical polyarthritis accompanying myositis, fever, weight loss, and malaise in a 15-year-old male patient. To our knowledge, this is the first case pediatric thymic carcinoma accompany with severe polyarthritis and myopathy, thus we have reviewed the current literature regarding the cases of thymic malignancies coexisting with paraneoplastic syndromes in children.

How Safe Are Biological Agents in Pediatric Rheumatology?

OBJECTIVE: Biologic therapy has changed the prognosis of patients with rheumatologic disease. Despite all benefits of the biological agents, adverse events may occur due to their long-term use. The aim of this study is to analyze the adverse events observed in pediatric patients who received biological treatment. MATERIALS AND METHODS: This retrospective observational cohort study was conducted between January 2010 and January 2022. File records of 139 patients used biological agents for rheumatologic diseases in a pediatric rheumatology clinic were evaluated. Diagnosis, received treatment, the rationale for stopping treatment, requirement of tuberculosis prophylaxis, presence of an adverse event, and results were recorded. RESULTS: The most used biological therapy was etanercept (41.7%). Anakinra, adalimumab, canakinumab were used in 30.9%, 27.3%, 23.7% of patients, and the others in less than 10%. Totally 491 adverse events (97.9/100 patient-years) were encountered during the duration of biological treatment. The most often adverse event was recurrent upper respiratory tract infection in the patients (31.9/100 patient-years). Elevated aminotransferase levels (10.4/100 patient-years), abdominal pain (7/100 patient-years), and headache (5.2/100 patient-years) were among the other common side effects. Isoniazid (INH) prophylaxis was needed before biological treatment in 20.9% of the patients. Tuberculosis developed in none of the patients followed-up for latent tuberculosis, however, it developed in a patient while receiving etanercept due to noncompliance with his scheduled outpatient visits during etanercept treatment. CONCLUSION: The most commonly used biological treatments were TNFi and IL-antagonists, and the majority of side effects were infections and laboratory abnormalities. Although the rate of serious adverse events is quite low, close follow-up of patients receiving biological therapy is very important.

Chronic Nonbacterial Osteomyelitis Associated With Familial Mediterranean Fever in Children.

OBJECTIVE: Chronic nonbacterial osteomyelitis (CNO) is a noninfectious autoinflammatory bone condition that frequently occurs alongside other inflammatory diseases, such as familial Mediterranean fever (FMF). We aimed to determine the demographic, clinical, laboratory, and radiological characteristics of patients diagnosed with both FMF and CNO. METHODS: We reviewed the medical records of pediatric patients with both CNO and FMF at 3 pediatric rheumatology centers in Turkey from December 2008 to 2022. Patients' demographics, laboratory features, imaging findings, and treatment were recorded. RESULTS: Twelve patients with FMF and CNO were included in the study. Half of them were female. The mean ages at onset for FMF and CNO symptoms were 80 and 116 months, whereas the ages at diagnosis for FMF and CNO were 100 and 125 months, respectively. Ten patients (83.3%) had M694V mutation on at least 1 allele of the Mediterranean fever (MEFV) gene. The most common sites of osteitis were the long bones (58.3%), pelvis (50%), and clavicles (25%). Ten patients (83%) received nonsteroidal anti-inflammatory drugs; 8 (66%) received disease-modifying antirheumatic drugs; biological therapy was administered to 5 patients (41%), who did not respond to these treatments; and all patients received colchicine. CONCLUSION: The increased frequency of FMF in patients with CNO is of interest. Because most patients with CNO and FMF carried a homozygous or combined heterozygous M694V mutation, we speculated that the M694V mutation may play a role in the development of osteitis. Further studies are needed to elucidate the link between FMF and CNO.

Adhesive small-bowel obstruction as a challenging complication of familial Mediterranean fever: A case-based review.

Familial Mediterranean fever (FMF) is the most common inherited autoinflammatory disorder, characterized by recurrent and self-limiting episodes of fever and serosal inflammation. Recurrent serositis may rarely lead to the formation of adhesions in the peritoneum, which may result in mechanical bowel obstruction. The symptoms, such as abdominal pain and vomiting, may mimic typical FMF attacks, resulting in misdiagnosis and severe morbidity, including strangulation and intestinal necrosis. Physicians are generally aware of other complications associated with FMF but reports on peritoneal adhesions and intestinal obstruction in English-language literature are inadequate to increase clinicians' awareness. Therefore, it is crucial to meticulously evaluate FMF patients presenting with abdominal pain and ileus because these symptoms could be due to adhesive small-bowel obstruction (ASBO). Furthermore, patients presenting with ASBO without a history of abdominal surgery should also be thoroughly evaluated, especially as it could be an initial presentation for an autoinflammatory disease. Herein, we present a pediatric case of FMF with the M694V homozygous mutation, complicated by ASBO while under colchicine treatment. Additionally, we provide a comprehensive review of the available literature on ASBO in FMF.

A possibly new autoinflammatory disease due to compound heterozygous phosphomevalonate kinase gene mutation.

BACKGROUND: Mevalonate kinase (MVK) plays a role in cholesterol and non-sterol isoprenoid biosynthesis and its deficiency-related diseases are caused by bi-allelic pathogenic mutations in the MVK gene, (MVK), which leads to rare hereditary autoinflammatory diseases. The disease may manifest different clinical phenotypes depending on the degree of the deficiency in the enzyme activity. The complete deficiency of the enzyme activity results in the severe metabolic disease called mevalonic aciduria, while a partial deficiency results in a broad spectrum of clinical presentations called hyper-immunoglobulin D syndrome (HIDS). Serum immunoglobulin (Ig) D and urine mevalonic acid levels may be increased during inflammatory attacks of HIDS. CASE PRESENTATION: Herein, for the first time in the literature, we present a 6-year-old male patient who suffered from recurrent episodes of fever, polyarthritis, skin rash, diarrhea, abdominal pain, and inflammatory bowel disease-like manifestations with elevated levels of serum IgD, and urine mevalonic acid. Eventually we detected compound heterozygous mutations in the phosphomevalonate kinase (PMVK) gene coding the second enzyme after mevalonate kinase in the mevalonate pathway. CONCLUSION: For patients presenting with HIDS-like findings, disease exacerbations and persistent chronic inflammation, and having high urinary mevalonic acid and serum IgD levels, raising suspicion in terms of MVK deficiency (MVKD), it is recommended to study all mevalonate pathway enzymes, even if there is no mutation in the MVK gene. It should be kept in mind that novel mutations might be seen such as PMVK gene.

Recurrent macrophage activation syndrome due to hyperimmunoglobulin D syndrome: a case-based review.

Hyperimmunoglobulin D syndrome (HIDS) is a hereditary autoinflammatory disease characterized by recurrent inflammatory attacks with fever, abdominal pain, lymphadenopathy, aphthous stomatitis, and skin lesions. There are few reports on HIDS patients complicated with macrophage activation syndrome (MAS); however, to our knowledge, there is no case of HIDS with recurrent MAS attacks. We report two pediatric patients initially diagnosed as Kawasaki disease and systemic juvenile idiopathic arthritis presented with recurrent MAS episodes with prolonged fever, skin rash, hepatosplenomegaly, cervical lymphadenopathy, aphthous stomatitis, headache, pancytopenia, hyperferritinemia, and hypofibrinogenemia, finally diagnosed as HIDS with a documented homozygous MVK gene mutation. This is the first report on recurrent MAS attacks due to HIDS in pediatric patients who were successful treated with corticosteroids and anti-IL-1 therapies. Thus, clinicians should be vigilantly investigated signs of autoinflammatory diseases in patients with recurrent MAS attacks during their disease course, and HIDS should be considered an underlying disease for triggering recurrent MAS attacks. We have also reviewed the current literature regarding HIDS cases complicated with a MAS attack and summarized their demographic, treatment, and outcome characteristics. Key points • Hyperimmunoglobulin D syndrome should be considered in differential diagnosis in patients who experienced recurrent macrophage activation syndrome attacks.

A case of aquaporin 2 R85X mutation in a boy with congenital nephrogenic diabetes insipidus.

Autosomal recessive nephrogenic diabetes insipidus (ARNDI) is a rare disease usually seen in patients with consanguineous parents. We report on a case of ARNDI in a patient with non-consanguineous parents who presented with recurrent febrile attacks. The differential diagnosis of ARNDI was made by desmopressin infusion test. A homozygous mutation, R85X, was detected in the aquaporin 2 gene (AQP2) of our patient, which has been described only once previously. This case is presented to stress that even male patients with non-consanguineous parents could have ARNDI with a AQP2 gene defect, and the desmopressin infusion test is useful for differential diagnosis.