Back
IRGN is due to glomerular deposits of circulating complexes, caused by non renal infections (bacteria, fungus, parasite and viruses). It is more common in adults, particularly older or immunocompromised people. Unlike the favorable evolution in children, a significant proportion of adults do not recover renal function. Immunosuppression is controversial as most resolve with specific treatment for infection.
LN is the most common form of renal injury in systemic lupus erythematosus (SLE) and affects between 50-70% of patients at some point in the disease. It is a major risk factor for morbidity and mortality, and up to 10% of patients will develop end stage renal disease. There are different histological classes, being the most frequent class IV. It is characterized by diffuse endocapillary and extracapillary proliferation with evidence of immunofluorescence (FI) deposits. The recommended treatment consists of corticosteroids along with another immunosuppressant.
A 62-year-old man with a history of pulmonary nodule (2019) presents a 3-month evolution characterized by progressive edema, adding dyspnea and oliguria in the last 15 days associated with erythema and lower right limb pain (RLP), so he consults our hospital. He was admitted with a diagnosis of RLP cellulite (SAMS rescue: antibiotic treatment), nephrotic syndrome (NS) (albumin 1.7 g/dl, Proteinuria 12gr/day) and AKI Kdigo III (urea 138 mg/dl, creatinine 4 mg/dl.) .Negative balance with diuretics was unresponsive so hemodialysis was needed on 3 occasions, with subsequent improvement (creatinine: 1.42 mg/dl).
He presents multiple infections episodes, including pleural fluid culture with rescue of Cryptococccus Neoformans receiving amphotericin B for 14 days, continued with fluconazole.
Renal biopsy (RB) was performed reporting GN mediated by antibodies with diffuse proliferative pattern, with the presence of subepithelial deposits, some of these have a "hump-like" IF structure: igG and C3 +++, C1q (-).
During hospitalization, rheumatology profile ANA 1/320 homogeneous nuclear pattern, Ac anti DNA positive, C3: 69 mg/dl, C4:11 mg/dl, Anti C1Q positive. ASTO less than 200 IU/m, negative viral serologies. Given the findings of a IRGN vs LN, it was decided to perform a new renal biopsy to define immunosuppressive behavior
RB: glomerulopathy with diffuse endocapillary proliferative pattern and focal extracapillary with immunoglobulin deposits and complement IgG, C3, C1q, IgA+ were present so it was interpreted as LN class IV, treatment with cyclophosphamide and corticosteroids is initiated.
Both the IRGN and the LN class IV share histological characteristics, which are difficult to distinguish. Diagnosis is essential because treatment differs. Although it presented multiple infections, associated with Hump-like deposits, the latter being characteristic but not exclusive to IRGN, probably reflecting complement deposit. Given that it met the EULAR/ACR criteria for SLE and presented a proliferative pattern in a second RB despite the treatment of infections, we conclude the diagnosis of LN.