Kidney stones have various forms, sizes and etiology. Common compositions are calcium oxalate or uric acid. Matrix stones are rare and primarily contain protein matrix (mucoprotein) along with smaller constituents of calcium and phosphate. Risk factors are recurrent urinary tract infection (UTI), previous stone surgeries and chronic renal failure.

 

CASE PRESENTATION 74 year old lady with hypertension and dyslipidemia, presented to us with kidney stones. Computed Tomography (CT) revealed irregular calcifications at left kidney upper and lower pole, measuring 2.3cm x 1.7cm x 2.4cm and 1.9cm x 2.6cm x 1.9cm, respectively. Retrograde intrarenal surgery was done, the stones had soft, matrix-like consistency. Despite attempts of laser lithotripsy, there were difficulties in retrieving the fragments. Reassessment CT confirmed residual stones measuring 1.0cm x 1.3cm x 1.4cm. Patient is planned for a re-do surgery for complete clearance.

DISCUSSION Matrix stones are associated with urea-splitting UTI, commonly caused by P. Mirabilis and E. Coli. Human immune response forms web-like scaffolds leading to precipitation of inorganic particulates and mineral deposits. It is difficult to distinguish between conventional stone and matrix stone with CT. Among the challenges are diagnosing and achieving complete clearance due to the gelatinous structure of the stone. Percutaneous nephrolithotomy (PCNL) has been described in literature for complete stone clearance.