Overlap of familial Mediterranean fever and autoinflammatory PLCG2-associated antibody deficiency and immune dysregulation in a Turkish patient

Autoinflammatory diseases encompass a group of inherited disorders characterized by genetic defects in innate immunity, and leading to uncontrolled systemic or organ-specific inflammation. While familial Mediterranean fever (FMF) is a common example prevalent in Mediterranean regions, autoinflammatory phospholipase C gamma 2 ( PLCG2 )-associated antibody deficiency and immune dysregulation (APLAID) is extremely rare. We aim to report the first case of co-occurrence of FMF and APLAID and discuss the clinical manifestations, immunological findings, and medical approach of the patient by reviewing the medical literature. A 36-year-old male patient visited our dermatology clinic with a history of recurrent pustular eruptions since childhood, aggravated in the last month. He had bronchiectasis, emphysema, and a diagnosis of FMF. Colchicine helped to control arthritis but did not resolve the pustular eruptions. Histopathological examination of the pustules revealed neutrophilic exudation, and microbial cultures were negative. The patient exhibited high C-reactive protein levels, mild lymphopenia, mildly low IgM levels, and a decreased CD4/CD8 ratio. Genetic analysis revealed a heterozygous c.2120C > A (Ser707Tyr) mutation in the PLCG2 gene. Daily anakinra 100 mg therapy regressed subsequent relapses of pustules within two months. In 28-month treatment, the patient experienced two relapses of pustular eruption, which resolved with short-term low-dose systemic corticosteroid treatment. In conclusion, we point out that a thorough immunological evaluation of patients with recurrent pustular eruptions and associated systemic symptoms is essential, even if a patient has already been diagnosed with an autoinflammatory disease. Albeit rare, it is important to consider the possibility of another coexisting autoinflammatory disease.