ABSTRACT
Introduction: IgG4-related diseases (IgG4-RD) are characterized by organomegaly, high IgG4 level and marked infiltration of IgG4(+) cells in the affected organs, with renal involvement in approximately 25% of cases. The coexistence of AAV with IgG4-RD has been reported in some case, while ANCA-associated vasculitis (AAV) is often associated with autoimmune diseases. There have also been some reports of new renal lesions caused by the COVID19 vaccine, such as minimal change disease, IgA nephropathy, and vasculitis, but there are still no reports of new-onset IgG4-RD. Case Description: A 61-year-old man developed fever, malaise, thirst and polydipsia the day after a second vaccination of COVID19 (mRNA-12733, Moderna). Blood test showed kidney dysfunction, high IgG4 level, and MPO-ANCA positivity. Brain MRI showed enlargement of pituitary gland. Salivary gland scintigraphy showed secretory impairment in the submandibular and parotid glands. CT scan revealed a rapid growing left renal tumor and CT-guided needle biopsy was performed. Renal specimens showed diffuse infiltrates of CD138(+) plasma cells in the interstitium. More than 40% of IgG(+) cells were IgG4-positive, accompanied by interstitial fibrosis with a "striform" pattern. Focal necrotic and granulomatous lesions were detected with tubular atrophy and tubulitis. Bowman's capsules were disrupted by massive interstitial inflammation in some glomeruli, but no obvious proliferative lesions. Finally, he was diagnosed as IgG4-RD and steroid therapy was started. Desmopressin was administered for central enuresis. The systemic symptoms were improved gradually and the renal tumor was reduced. Discussion(s): In this case, it is suggested that immunological changes caused by the vaccine or allergic reaction to the vaccine may trigger the onset of the disease. Elevated MPO-ANCA titer and tubulointerstitial nephritis with necrotic and granulomatous lesions may have been associated with AAV. However, the patient had renal tumor with characteristic pathological findings of IgG4-RD, accompanied by hypophysitis and sialadenitis. We concluded that the main condition in our case is IgG4-RD. IgG4-related kidney disease after COVID-19 vaccination is extremely rare. Careful monitoring after the COVID19 vaccine is important with immunological abnormalities.