EARLY PRESENTATION OF SECONDARY SELECTIVE IGM DEFICIENCY - LIKE THE SPREADING CRACK ON A DAM

Introduction: Selective IgM deficiency (SIgMD) is characterized by low IgM, with prevalence around 0.03-3.8%1,2. Associated diseases include atopy, fibromyalgia-like symptoms, autoimmunity, and malignancies3,4. There has also been an association of impaired PPSV23 response.3 SIgMD have been described progressing to common variable immunodeficiency (CVID) in an average of 3 years in a longitudinal study5. This describes an early presentation of SIgMD. Case Description: A 67yo male with a history of rheumatoid arthritis (RA), diabetes type 2, and interstitial lung disease (ILD) was referred to immunology January 2019 for recurrent infections. Patient had no significant infections before January 2018 when he developed pneumonia. He subsequently developed 2 more cases of pneumonia in 6 months as well as pyelonephritis resulting in hospital admission and IV antibiotics. On our initial evaluation, patient was being treated for his RA with leflunomide 20mg daily and hydroxychloroquine 400mg daily. He had initial IgM of 25 mg/dl, repeat of 22mg/dl and elevated IgG6. Initial PPSV23 titers were 48% positive with repeat after vaccination 39% positive. Remainder of laboratory values were unremarkable. CT Chest was suggestive of ILD. Discussion: SIgMD has been shown to improve with treatment of the underlying associated condition. In this case the patient’s RA is currently well controlled but low IgM and recurrent infections persist and are becoming more frequent. SIgMD deficiency has been reported progressing to CVID. This case demonstrates the importance of close follow up in patients with SIgMD to allow early intervention as needed. [Figure presented]