title: Renal matrix stone managed by ureteroscopic holmium laser lithotripsy.
abstract: BACKGROUND
  Matrix stones are rare types of urinary calculi composed of mucoproteins and mucopolysaccharides. Since isolated flank pain may be the only presenting symptom and routine radiographic studies are usually non-informative, diagnosis of such urinary calculi represents a clinical challenge. Traditionally, these matrix stones have been managed by either open pyelolithotomy or percutaneous nephrolithotomy (PCNL). Ureteroscopic management of a patient with matrix renal stones and review of literature is presented.
  
  
  METHODS
  A 34-year-old woman presented with chronic right flank pain. Abdominal ultrasound found a 5.3 cm heterogeneous right renal pelvic mass with 9.7 mm stone. CT urogram confirmed the filling defects. Diagnosis of matrix stones was made using ureteroscopy. During ureteroscopy and holmium laser lithotripsy, a 13/15F ureteral access sheath was placed and the matrix stones were irrigated out. She required outpatient shockwave lithotripsy for the residual radio-opaque stone. A second-look ureteroscopy confirmed stone free status.
  
  
  CONCLUSIONS
  Matrix renal stones present a diagnostic challenge. Although PCNL is the gold standard of therapy for large renal matrix stones, ureteroscopy could also be used for both diagnosis and laser lithotripsy. In the present case, ureteral access sheath was used to irrigate the mucinous matrix stone material.
authors.affiliation: Division of Urology, McGill University Health Centre, Montreal, Quebec, Canada.
authors.forename: Carlos H F
authors.initials: CH
authors.lastname: Chan
authors.forename: Assaad
authors.initials: A
authors.lastname: El-Hakim
authors.forename: Sero
authors.initials: S
authors.lastname: Andonian
mesh_terms: D000328:Adult; D000535:Aluminum; D005260:Female; D006695:Holmium; D006801:Humans; D007669:Kidney Calculi / Q000150:complications / Q000601:surgery*; D017602:Lithotripsy, Laser / Q000009:adverse effects / Q000379:methods*; D016896:Treatment Outcome; D018666:Ureteroscopy; D015019:Yttrium
chemical_list: C503779:yttrium-aluminum-garnet; D015019:Yttrium; D000535:Aluminum; D006695:Holmium