Soft Renal Calculi (Matrix Stones)
Soft calculi or so called matrix calculi appear to be very rare. Less than 50 cases have been published. The matrix substance A (mucoprotein), which usually represents only 2,5% of the weight of fully calcified stones can reach 65% in soft calculi. However, there is no difference in the architectural arrangement of the matrix skeleton between the two types of lithiasis.
Soft calculi belong to infective renal calculi in which neither metabolic disturbances nor intratubular matrix precursor can usually be found. Calculogenesis starts in the major collecting system. The polymerisation of urine mucoprotein, induced by urea-splitting infection, produces a calculogenic matrix substance. Precipitation of apatite also occurs. The immature matrix calculus, initially plastic (soft), will eventually develop to form a phosphatic staghorn calculus.
Our experience, based on 25 cases of soft calculi, is rather similar to previous reports, except for some particular points, such as the participation of oxalic or uric crystals in the calculogenesis of soft calculi. Our renal biopsy findings are described.
Among these 25 cases, 9 can be considered as “malignant” (leading to renal failure or life threatening). The surgical treatment requires complete removal of the stones, control of the urinary infection and the prevention of recurrences by fibrinolytic and mucolytic infusion in the major collecting system.
KeywordsRenal Calculus Urinary Tract Obstruction Uric Crystal Retrograde Pyelography Nephrostomy Catheter
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