A case report of Hyper-IgD syndrome in a 5-year-old girl with recurrent fever, skin rash, and arthralgia; novel MVK mutation (C.298G>A).

Key Clinical Message: This case highlights the potential for later-onset Hyper-IgD syndrome (HIDS) even beyond infancy. Clinicians evaluating children with recurrent fever, skin rash, and arthralgia should consider HIDS in the differential diagnosis, regardless of age. Early suspicion and genetic testing can lead to a timely diagnosis and targeted therapy with Anakinra, significantly improving patient outcomes. Abstract: Hyper-IgD syndrome (HIDS) is a rare autosomal recessive autoinflammatory disorder characterized by recurrent episodes of fever, lymphadenopathy, arthralgia, diarrhea, abdominal pain, and skin rash. In this case report, we present a 5-year-old girl from Tajikistan with a mutation in the mevalonate kinase (MVK) gene, which is consistent with a diagnosis of HIDS. The clinical symptoms of the patient are described, along with immunological, hematological, and biochemical findings collected from the evaluation in the rheumatology clinic. Additionally, whole-exome sequencing revealed a heterozygous missense variation in exon 4 of the MVK gene. The diagnosis of HIDS in this case occurred at a later age than typically observed, emphasizing the importance of considering this condition even in older patients. This report highlights the broad clinical phenotype of MVK and the need for increased awareness among healthcare professionals regarding its clinical presentation and management.

Case report of streptococcal infection as a potential precipitating factor in cutaneous polyarteritis nodosa in pediatric patients.

Key Clinical Message: This pediatric case report underscores the importance of maintaining a high clinical suspicion for polyarteritis nodosa (PAN) in patients presenting with atypical features, such as migratory arthritis and subcutaneous nodules. Importantly, it highlights the focus on the potential relationship between streptococcal infection and cutaneous PAN. Early recognition and prompt, aggressive treatment is critical, as PAN can be a life-threatening condition if left unmanaged. This case emphasizes the need for a multidisciplinary approach to effectively identify and manage this rare vasculitis disorder in the pediatric population. Abstract: Polyarteritis nodosa (PAN) is a rare and life-threatening vasculitis with diverse clinical presentations, posing a diagnostic challenge. Early recognition and prompt intervention are crucial to prevent organ damage. We present the case of an 8-year-old boy who exhibited atypical symptoms including migratory arthritis, myalgia, digital discoloration and ischemic changes, and subcutaneous nodules. Initial concerns for septic arthritis were ruled out. A comprehensive evaluation revealed elevated inflammatory markers and a confirmatory skin biopsy demonstrating active leukocytoclastic vasculitis, are highly suggestive of a diagnosis of PAN. Notably, elevated ASO titers suggested a possible concurrent streptococcal infection. The aggressive treatment approach with high-dose aspirin, steroids, methotrexate, and tocilizumab is justified given the severity of the patient's symptoms and the nature of the disease process. This case underscores the importance of considering PAN in the differential diagnosis for children presenting with atypical features. Early diagnosis and prompt intervention, including addressing potential infectious triggers, are crucial for optimal outcomes in pediatric PAN.