Medullary sponge kidney and staghorn calculi

Area of Science:

• Nephrology
• Urology
• Infectious Diseases

Background:

• Medullary sponge kidney (MSK) disease is a congenital renal disorder characterized by cystic dilatation of the medullary and papillary portions of the collecting ducts.
• MSK disease is associated with several risk factors for nephrolithiasis, including urinary stasis, altered urine composition, and increased susceptibility to infection.
• Staghorn calculi, large kidney stones cast in the renal pelvis and calyces, are often linked to complex urinary tract infections and metabolic abnormalities.

Observation:

• A 65-year-old female presented with a Proteus mirabilis perinephric abscess.
• Radiologic imaging revealed bilateral staghorn calculi and findings consistent with underlying medullary sponge kidney (MSK) disease.
• The abscess was secondary to a ruptured lower pole hydrocalyx, indicating a complex interplay of infection and urinary tract obstruction.

Findings:

• The coexistence of bilateral staghorn calculi and MSK disease is uncommon, despite MSK presenting numerous risk factors for stone formation.
• Proteus mirabilis, a urease-producing bacterium, likely contributed to the rapid formation and complexity of the staghorn calculi and the subsequent perinephric abscess.
• The ruptured hydrocalyx served as a nidus for infection and stone propagation, leading to a severe perinephric abscess.

Implications:

• This case highlights the importance of considering MSK disease in patients with complex staghorn calculi, even when the association is considered rare.
• Understanding the specific risk factors and pathogenic mechanisms in such cases may lead to improved diagnostic and therapeutic strategies for MSK-related nephrolithiasis and infections.
• Further research into the pathophysiology of MSK disease and its interaction with specific bacterial pathogens like Proteus mirabilis is warranted to elucidate the reasons for the infrequent coexistence of staghorn calculi.