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The diagnosis of paraneoplastic glomerulonephritis (PGN) is challenging and often delayed, which can lead to significant morbidity and mortality. Paraneoplastic glomerulonephritis is a rare complication of a malignant tumor, with glomerular lesions that are not directly related to tumor burden, invasion or metastasis, but are induced by products of tumor cells. PGN can be the initial presentation of renal cell carcinoma (RCC) or a sign of recurrence. The association of ANCA associated vasculitis with solid tumors has been sporadically reported, but cancers are frequently diagnosed after the initial diagnosis of vasculitis. We describe a case of RCC that presented ANCA associated vasculitis 6 months after diagnosis of renal cancer.
A 51-year-old male with hypertension and a kidney tumor diagnosed on January 2023 in study protocol by oncology with baseline creatinine 1.8 mg/dl, family history of RCC (sister). In May 2023, with nausea, diarrhea, sudden decrease of urine output and worsening in renal function (SCr 21.46 mg/dl, K 6.5 mEq/L) due to uremic syndrome and hyperkalemia, renal replacement therapy was started. Approach was performed excluding obstructive and prerenal causes. With rapidly progressive glomerulonephritis (RPGN) and serology positive for perinuclear antineutrophil cytoplasmic antibody (P-ANCA) and myeloperoxidase (MPO). With no recovery of renal function, so prior to surgery, we treated the patient with steroids and cyclophosphamide, subsequently the induction was modified to rituximab, at the same time the renal tumor was approached with partial nephrectomy in July 2023.
Renal biopsy showed crescentic pauci-immune glomerulonephritis with interstitial fibrosis (30-40%) and clear cell RCC (TMN: PT1B) He is currently being followed up with remission induction therapy with rituximab, without recovery of renal function on hemodialysis 3 times at week. PGN associated with RCC is rare. In the reports published over four decades there are 10 cases. The results showed that patients who were treated with cancer-specific therapy combined with immunosuppression had a better outcome than those who were treated with nephrectomy, systemic therapy, or immunosuppression alone. In our patient the treatment involved nephrectomy and immunosuppression nevertheless the kidney function did not improve and partial remission of vasculitis.
The course of paraneoplastic glomerulonephritis is a diagnostic and therapeutic challenge, so early identification and treatment with close follow-up could help improve an already complex prognosis. Given the high morbidity and mortality associated with AAV, along with planned cancer treatment, we would have to treat ANCA-associated vasculitis with standard immunosuppression, including steroids and/or cyclophosphamide and/or rituximab to prevent irreversible damage of the kidney. In the absence of a diagnostic tool, a high degree of clinical suspicion continues to be paramount in the diagnosis and management of PGN.