title: Matrix calculi.
abstract: Matrix calculi are an uncommon form of urinary tract concretion. They must be considered in the differential diagnosis of a radiolucent mass within the renal collecting system or ureter. The clinical and radiographic features of three cases are presented and the literature of matrix calculi is reviewed.
mesh_terms: D001437:Bacteriuria / Q000382:microbiology; D002118:Calcium / Q000652:urine; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009088:Mucoproteins / Q000032:analysis; D011379:Prognosis; D011513:Proteus mirabilis / Q000302:isolation & purification; D011514:Proteus vulgaris / Q000302:isolation & purification; D011859:Radiography; D014514:Ureteral Calculi / Q000000981:diagnostic imaging; D014545:Urinary Calculi / Q000000981:diagnostic imaging*
chemical_list: D009088:Mucoproteins; D002118:Calcium