Matrix Stone

Radiolucent Matrix Stones in a Transplanted Kidney: A Case Report

Matrix stones are a rare form of kidney stones, which are composed of mucoproteinaceous material. They are often difficult to diagnose as they are characteristically radiolucent on CT urinary tract. This difficulty is compounded in transplanted kidneys as obstructing stones commonly present without pain and can cause acute kidney injury. Here, we present a case of a 61-year-old female with a live-donor kidney transplant, who was found to develop deranged renal function on routine follow-up investigations. Therefore, a CT urogram was performed and it showed filling defects in the renal pelvis and upper ureter of the transplanted kidney. Therefore, diagnostic ureterorenoscopy was performed and three stones of about 7-8 mm each were found in the renal pelvis, they were treated by Holmium:Yttrium aluminium garnet (YAG) laser fragmentation. This case report describes the challenges in the management of this rare stone in a transplanted kidney.

Comparison of Perioperative Outcomes and Clinical Characteristics of Calcium, Matrix and Struvite Stones From a Single Institution

OBJECTIVE

To define risk factors and perioperative outcomes for matrix stones and compare these outcomes with struvite and calcium stone cohorts.

METHODS

A retrospective cohort study comparing matrix stones (n=32), struvite stones (n=23) and a matched, calcium stone control group (n=32) was performed. Two-way ANOVA was used to compare the groups for continuous variables. Chi-square tests were used to compare categorical variables. Significance was set at P <.05. All statistical tests were performed using R (v1.73).

RESULTS

We identified no differences in age, gender, or BMI between the three groups. Matrix and struvite stones were more likely to have a history of prior stone surgery and recurrent UTIs compared to calcium stones (P=.027 and P <.001, respectively). Struvite stones were more likely to present as staghorn calculi compared to matrix or calcium stones (56.5% vs 21.7% vs 18.8%, P=.006). There were no significant differences in postoperative stone free rates (P=.378). No significant differences in postoperative infectious complications were identified. Matrix stones were more likely to have Candida on stone culture compared to the struvite or calcium stones (P <.0001).

CONCLUSION

Matrix and struvite stones were more likely have a history of stone surgery and preoperative recurrent UTIs. Struvite stones were more likely to present as staghorn calculi. Matrix stones were more likely to have Candida present in stone cultures. However, no difference in postoperative infectious outcomes or stone free rates were identified. Further study with larger cohorts is necessary to distinguish matrix stone postoperative outcomes from struvite and calcium stones.

Matrix Stone Occupying an Entire Renal Collecting System: A Case Report and Video of Diagnostic Ureterorenoscopy

Renal matrix stones are a rare phenomenon and they present a diagnostic challenge due to their atypical radiological appearances in comparison to more commonly encountered renal tract calculi. We describe a case of known stone former presenting with loin pain and recurrent urinary tract infections who was diagnosed with a matrix stone. The video of the diagnostic flexiureterorenoscopy demonstrating the matrix stone occupying almost the entire right renal collecting system is also presented.

Bilateral kidney matrix stones: a rare case

Kedney matrix stones are a rare form of calculi. Flank pain and urinary tract infections (UTI) are the most common presentations of matrix calculi. The diagnosis is usually made at surgery, but some preoperative radiographic findings might be suggestive. Open surgery was the method of choice for treatment. However, combination of ureterorenoscopy and percutaneous nephrolithotomy (PCNL) was found to be safe and effective. We report a rare case of renal and ureteral matrix stones that were diagnosed and treated by open surgery. We also describe its clinical, radiological and therapeutic features through a review of the literature.

Computed tomography in the nontraumatic renal causes of acute flank pain

Renal colic pain due to obstructing stone is the main renal cause of acute flank pain. However, other causes may be responsible for the same clinical findings, including acute pyelonephritis, acute vascular conditions, and hemorrhage. The purpose of this review is to describe the differential diagnosis, the computed tomographic findings and pitfalls, and the role and impact of computed tomography in the diagnosis and management of the renal causes of acute flank pain.

Renal matrix stones in an emphysematous pyelonephritis

A 74-year-old-woman was referred to our hospital for further examination. Her chief complaint had been a high-grade fever, but she was seen at our hospital without fever. Plain fi lm of kidney, ureter and bladder drip infusion pyelography and abdominal computed tomography (CT) showed a gas shadow surrounding calcifications in the right renal pelvis. We diagnosed right emphysematous pyelonephritis. Since changes in the CT findings were not remarkable for 2 weeks, we performed laparoscopic right nephrectomy, even though her condition had not worsened. The renal pelvis contained brownish and clayish matter. We report here this rare case of renal matrix stones.

[Retroperitoneoscopy to extract an amorphous matrix calculus of the right kidney]

The female patient underwent multiple extracorporal shockwave treatments and an ureterorenoscopy during which an amorphous renal mass was found. A retroperitoneoscopy was performed with extraction of a large amorphous matrix calculus. Today, the prevalence of matrix calculi is very low. They are associated with and caused by urinal-infections. Delayed diagnosis in radiological-imaging procedures is typical for these stones. The minimal-invasive approach via retroperitoneoscopy seems to be an intriguing alternative to the established procedures like percutaneous nephrolitholapaxy.

Evidence against a contribution of conventional urine risk factors to de novo ESRD renal stones

BACKGROUND

The authors measured urine and blood stone risk factors in African-American (AA) haemodialysis (HD) patients with new onset of stones during dialysis.

METHODS

Patients with nephrolithiasis (NL) newly manifested during dialysis were matched by age, sex and urine output and dialysis duration to AA HD patients without history or symptoms of stones. Two 24 h urine and serum samples were collected and analysed for conventional stone risk factors.

RESULTS

Three percent of the patients formed new stones while on HD; none had formed stones prior to end-stage renal disease. Newly onset NL patients had higher urine citrate and lower serum potassium levels than HD patients without stones.

CONCLUSION

Usual stone risk factors did not correlate with new stones during dialysis.

Mimics of Renal Colic: Alternative Diagnoses at Unenhanced Helical CT

During the past decade, unenhanced computed tomography (CT) has become the standard of reference in the detection of urinary calculi owing to its high sensitivity (>95%) and specificity (>98%) in this setting. Numerous diseases may manifest as acute flank pain and mimic urolithiasis. Up to one-third of unenhanced CT examinations performed because of flank pain may reveal unsuspected findings unrelated to stone disease, many of which can help explain the patient's condition. Alternative diagnoses are most commonly related to gynecologic conditions (especially adnexal masses) and nonstone genitourinary disease (eg, pyelonephritis, renal neoplasm), closely followed by gastrointestinal disease (especially appendicitis and diverticulitis). Hepatobiliary, vascular, and musculoskeletal conditions may also be encountered. Vascular causes of acute flank pain must always be considered, since these constitute life-threatening emergencies that may require the intravenous administration of contrast material for diagnosis. Radiologists must be familiar with the typical findings of urinary stone disease at unenhanced CT, as well as the spectrum of alternative diagnoses that may be detected with this modality, to accurately diagnose the source of flank pain.