BK virus nephropathy in a native kidney.

Area of Science:

• Nephrology
• Virology
• Immunology

Background:

• BK virus (BKV) is a polyomavirus linked to kidney transplant dysfunction.
• Following initial infection, BKV establishes latency in the renal and urinary tract epithelium.
• In immunocompetent individuals, BKV infection typically causes no significant pathology.

Purpose of the Study:

• To report the first non-malignancy, non-transplant-associated pediatric case of BK virus nephropathy in a native kidney.
• To underscore the significance of considering BK virus infection in the differential diagnosis of nephropathy in pediatric patients undergoing chronic immunosuppression.

Main Methods:

• Case presentation of an 11-year-old female with a severe autoimmune/inflammatory condition requiring chronic immunosuppression.
• Diagnosis of BK virus nephropathy was confirmed through elevated serum creatinine, BK viruria and viremia, kidney biopsy findings (multifocal lymphocytic tubulitis, cytonuclear changes), and positive SV40 immunohistochemical staining.

Main Results:

• The patient presented with persistently elevated serum creatinine, indicating impaired kidney function.
• Kidney biopsy revealed characteristic signs of BK virus nephropathy, including tubulitis and specific cellular changes.
• Immunohistochemistry confirmed the presence of the virus, leading to the diagnosis.

Conclusions:

• This case represents the first documented instance of BK virus nephropathy in a native kidney in a pediatric patient, unrelated to malignancy or transplantation.
• The findings emphasize the need for clinicians to consider BK virus infection in the differential diagnosis of kidney disease in children receiving long-term, high-dose immunosuppressive therapy for various conditions.