Nephrotic syndrome and renal failure in a patient with metastatic breast cancer.

This report presents a case of nephrotic syndrome and renal failure that developed in a 53-year-old female with metastatic breast carcinoma. She was diagnosed to have osteolytic bone metastases 5 years prior to admission, and had been administered pamidronate with a total dose of approximately 6800 mg. A renal biopsy revealed tubulointerstitial damage and marked wrinkling and retraction of the glomerular basement membrane with hypertrophy and hyperplasia of the epithelial cells, compatible with the collapsing form of focal segmental glomerulosclerosis (FSGS). Despite the discontinuation of pamidronate after admission, her renal function gradually decreased. She was finally managed with continuous palliative care for advanced malignancy through a shared effort, and died 96 days after undergoing the renal biopsy. Although the clinical impact of the pamidronate-associated kidney injury on the longitudinal changes in renal function remains to be delineated, it is therefore reasonable to consider that the collapsing FSGS associated with tubulointerstitial damage may have resulted in the irreversible renal injuries that were observed in the current case. Further studies and accumulated experience with renal biopsy are required to better determine the relationship between pathological alterations and prognostic characteristics among patients with pamidronate-associated renal impairments.