A rare case of combined kidney damage in a patient with neurofibromatosis type 2

Background : neurofibromatosis type 2 (NF2) is a rare autosomal dominant disorder characterized by the formation of multiple tumors in the central and peripheral nervous system. Kidney involvement in NF2, including the formation of renal sclerosing peritubular nodules (RSPN), is uncommon and typically subclinical. Most of previous descriptions of this renal changes are based on the results of autopsy studies of patients who died from NF2. Case presentation : we report a 21-year-old patient with a confirmed diagnosis of NF2 treated with bevacizumab who developed combined kidney injury. Renal involvement was detected during a routine follow-up 14 months after initiating bevacizumab therapy and manifested as persistent proteinuria (1.0-3.6 g/day) and significant hematuria. Kidney biopsy revealed a combined lesion consisting of RSPN and IgA nephropathy with focal proliferative and sclerosing features. Morphological interpretation required evaluating the contribution of each lesion to disease progression and determining whether the glomerulonephritis was primary or secondary to the underlying disorder or therapy. Despite the potential association of renal pathology with ongoing bevacizumab therapy, treatment could not be discontinued due to the worsening clinical manifestations of NF2. Over time, renal function gradually declines (serum creatinine 128-303 mmol/L). Second kidney biopsy demonstrated increased glomerulosclerosis and interstitial fibrosis. Conclusion : this case illustrates previously unreported combined kidney damage – renal sclerosing peritubular nodules and IgA nephropathy – in a patient with NF2 undergoing bevacizumab therapy.