ABSTRACT
Introduction: Despites reports of glomerulonephritis associated with COVID-19 mRNA vaccines, no study has reported about the dense deposit disease (DDD). Here we present a case of pseudolung cancer lymphadenopathy following COVID-19 mRNA vaccine, following which the patient developed idiopathic tubulointerstitial nephritis (TIN) and DDD. Case Description: A 74-year-old man received his second dose of the mRNA vaccine, and he developed fever, urticaria, and dyspnea. On further examination, he had pleural effusion and right hilar lymphadenopathies, which were improved with conservative therapy. On 48 days after the second vaccination, he developed renal dysfunction and new-onset hematuria. Light microscopy findings by a renal biopsy demonstrated apparent mesangial cell proliferation and diffuse inflammatory cell infiltration in the interstitium. Immunofluorescence analysis revealed 1+ positive results for IgG and IgM, negative results for IgA, and 2+ positive results for C3 with a garland pattern on the capillary walls. Electron microscopy detected that continuous and thickened highly dark-stained spotty dense deposits in the glomerular basement membrane. Based on the decrease in C3 and pathological findings, idiopathic TIN accompanied with DDD was diagnosed. Discussion(s): After vaccination acute allergic reaction, pseudolung cancer lymphadenopathy, hematuria, and hypocomplementemia were observed. Thus, both coincidental onset with DDD and TIN following acute allergic response that occurred about 7 weeks before made us think that each event or disease might be associated with COVID-19 mRNA vaccination as part of immunological reactions. In complement activation related pseudoallergy syndrome, it is recently recognized that several modernday therapeutic molecules may activate complements via the nonIgE mediated mechanism with the C3a and C5a anaphylatoxins binding to mast cells, triggering that the release of a number of several vasoactive mediators that cause the clinical features associated with hypersensitivity reactions. mRNA vaccine might have contributed to the development of lymphadenopathies, TIN and DDD in this case. Moreover, TIN and DDD might be associated with the activated alternative pathway induced by the mRNA vaccine.