Adalimumab-Associated Pauci-Immune Glomerulonephritis: Coincidence or Causation Effect?

Introduction: Adalimumab is a TNF-blocker used in the treatment of hidradenitis suppurutiva (HS) Infections, lupus-like syndrome, and lymphoma are known safety concerns with TNF-blockers We report a rare case of adalimumab associated pauciimmune crescentric GN (PICGN) in a patient with HS Case Description: A 19-yr-old male with a history of HS on adalimumab for 6 months was seen on 4/1/20 with a fever of 103°F, cough & epistaxis for 2 weeks CT sinuses showed polyps and sinusitis He was treated with antibiotics for sinusitis CT chest, nasal PCR for COVID-19, blood, and urine cultures were negative By hospital day 8, he remained febrile and developed AKI [Creatinine (Cr)1 9 mg/dl;baseline of 0 8 mg/dl] Physical exam showed chronic scarred skin lesions on the chest and axilla with no signs of infection or rash Hematuria and microalbuminuria were noted Ultrasound showed renomegaly Inflammatory markers were high (CRP 254 mg/L, Ferritin 1059 ng/ mL) PR3-ANCA antibody was positive 530 IU/mL A renal biopsy confirmed PICGN (Fig 1) Bone marrow biopsy showed no evidence of hemophagocytosis The patient was treated with pulse doses of steroids and rituximab and plasma exchange (peak cr 6 4 mg/dl) On a 3-week follow up creatinine improved to 1 8 mg/dl suggesting a favorable outcome The patient never required dialysis Discussion: AKI, microscopic hematuria, and proteinuria can be seen in a febrile illness However, epistaxis and renomegaly prompted us to check for ANCA serology To our knowledge, this is the first case of adalimumab associated PICGN in a patient with HS Interestingly, our patient is much younger compared to previously reported cases (mean 51 4 years) It is possible that adalimumab may be unrelated to the vasculitis;however, due to a strong temporal association, it was felt to be the culprit agent Nephrologists must be aware of the renal side effects of this class of drugs (Figure Presnted) (Figure Presented)