• Guo-Min Li, Hai-Mei Liu, Wan-Zhen Guan, Hong Xu, Bing-Bing Wu, Jia-Yan Feng, and Li Sun.
• Department of Rheumatology.
• Medicine (Baltimore). 2019 May 1; 98 (18): e15329e15329.

RationaleGain of function (GOF) mutations in PIK3CD gene encoding PI3K p110δ were recently associated with a novel combined immune deficiency characterized by recurrent sinopulmonary infections, CD4 lymphopenia, reduced class-switched memory B cells, lymphadenopathy, cytomegalovirus and/or epstein-Barr virus (EBV) viremia, and EBV-related lymphoma. A subset of affected patients also had elevated serum IgM.Patient ConcernsWe report a patient who was diagnosed with systemic lupus erythematosus (SLE) at a young age and was recently found to carry heterozygous mutations in PIK3CD. The patient not only presented with recurrent sinopulmonary infections, CD4 lymphopenia, lymphadenopathy, EBV viremia, and elevated serum IgM, but also met classification criteria of SLE based on persistent proteinuria and hematuria, leukopenia and anemia, low level of serum complement, and positive autoantibody for antinuclear antibodies.DiagnosesActivated PI3Kδ syndrome.InterventionsOral prednisolone and hydroxychloroquine combined with mycophenolate mofetil was given to the patient. He was currently receiving intravenous immunoglobulin per month in association with hydroxychloroquine, low-dose prednisolone, and mycophenolate mofetil.OutcomesAt present, the level of complement restored to normal, hematuria and proteinuria disappeared, and liver function returned to normal.LessonsSLE may be a novel phenotype of GOF mutation in PI3CKD gene (GOF PIK3CD).

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