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The kidneys and urinary bladder are continuous, connected by the ureters.  The common mucosal lining is termed transitional epithelium, having a superficial resemblance to squamous epithelium.  The kidney biopsy is one of the few tissues in surgical pathology where routine examination involves light microscopy with H and E and special stains, electron microscopy, and direct immunofluorescence. 

Urinary bladder pathology is often used in conjunction with urine cytology which may involve voided urine or a bladder washing.  In this latter procedure, sterile saline is introduced into the bladder and evacuated and submitted for cytological analysis by the pathologist.

Alport Syndrome
Angiomyolipoma of the Kidney
Chromophobe Renal Cell Carcinoma of the Kidney
Clear Cell Sarcoma of the Kidney
Congenital Mesoblastic Nephromas
Diabetes Insipidus
End Stage Renal Disease (ESRD)
Eosinophilic Cystitis
Fabry Disease
Glomerulonephritis (Glomerulopathies)
Idiopathic Retroperitoneal Fibrosis
Kidney Stones
Malignant Rhabdoid Tumor of the Kidney
Mesoblastic Nephroma
Metanephric Adenoma
Metanephric Stromal Tumors
Nephrogenic Adenoma
Polycystic Kidney Disease
Renal Cell Carcinoma (Adenocarcinoma of the Kidney)
Stones (Calculi)
Syndrome of Inappropriate Anti-Diuretic Hormone (SIADH)
Transitional Cell Carcinoma of the Renal Pelvis
Urinalysis (U/A)
Urinary Bladder Carcinoma (Transitional cell CA, Adenocarcinoma, Squamous cell CA)
Urinary Bladder Lymphoma
Wilms' Tumor


Laboratory/Radiologic/Other Diagnostic Testing


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Occurrence of urinary tract infection in patients with renal allograft biopsies showing neutrophilic tubulitis.

Fonseca LE Jr, Shapiro R, Randhawa PS.

Department of Anatomic Pathology & Legal Medicine (LEF), Bahia Federal Medical School, Salvador, Bahia, Brazil.


Mod Pathol 2003 Apr;16(4):281-5 Abstract quote

Lymphocytic tubulitis is a well-accepted criterion for acute cellular rejection in renal allograft biopsies. Neutrophilic tubulitis has been used as a surrogate marker for urinary tract infection, but it is not clear how reliably this lesion can be used to make this diagnosis.

Biopsy findings were correlated with clinical features in 26 renal allograft biopsies with interstitial polymorphonuclear infiltrates associated with neutrophilic tubulitis. The grade of neutrophilic tubulitis exceeded the grade of lymphocytic tubulitis in 7 (44%) of 16 patients with, but in only 0 patients without, a positive urine culture. Culture confirmed urinary tract infection in 16 (62%) of 26 patients. It is possible that prior antibiotic therapy led to a false-negative culture and masked the diagnosis in two additional patients. Lymphocytic tubulitis made it difficult to exclude concurrent acute cellular rejection in all biopsies studied. In 6 (23%) of 26 patients, negative cultures and response to steroid treatment confirmed that neutrophilic tubulitis can occur in biopsies without urinary tract infection. The relative contributions of infection and rejection could not be determined in patients treated with both steroids and antibiotics.

Neutrophilic tubulitis in a renal allograft biopsy should alert the clinician to the possibility of urinary tract infection, even if concurrent lymphocytic tubulitis is present. Confirmation by urine culture is needed because biopsies with ischemic injury and acute cellular or antibody-mediated rejection can show overlapping histology.


Intraoperative Consultation for Renal Lesions Implications and Diagnostic Pitfalls in 324 Cases

Bhuvaneswari Krishnan, MD, Juan Lechago, MD, PhD, Gustavo Ayala, MD, and Luan Truong, MD
Am J Clin Pathol 2003;120:528-535 Abstract quote

Intraoperative consultation rarely is requested for lesions in the kidney. Of 324 renal lesions submitted for gross or frozen section intraoperative consultation, 199 specimens were submitted for gross consultation only; no diagnostic pitfalls were noted.

The clinical implications and diagnostic pitfalls in 125 specimens submitted for frozen section were the focus of our study. Frozen section intraoperative consultation was requested to evaluate surgical margins in partial nephrectomy specimens, solid renal mass in an unusual clinical or radiologic setting, synchronous renal and extrarenal masses, cystic renal lesion, ureteral surgical margins for transitional cell carcinoma, multiple renal masses, solid mass in a diffusely cystic kidney, and renal injury. Among the 125 cases, the diagnoses were deferred in 17 (6 renal cell carcinomas with granular cytoplasm, 7 cystic lesions, 3 metastatic tumors, 1 leiomyoma).

The frozen section diagnoses were incorrect owing to limited sampling in 5 and misinterpretation in 4 (melanoma vs angiomyolipoma, lymphoma vs angiomyolipoma, benign cyst vs cystic renal cell carcinoma, metastatic renal cell carcinoma vs pheochromocytoma).

Awareness of distinctive indications for frozen section intraoperative consultation and diagnostic pitfalls should improve diagnostic accuracy and facilitate proper management of these lesions.
Practice guidelines for the renal biopsy.

Walker PD, Cavallo T, Bonsib SM.

1Nephropathology Associates, Little Rock, AR, USA.

Mod Pathol. 2004 Dec;17(12):1555-63. Abstract quote

Biopsy of the kidney should never be undertaken without careful consideration of the risks vs benefits. Given the importance of a correct diagnosis in the treatment and prognosis of renal disease, the pathological evaluation should use all available modalities. Native kidney biopsies require examination by light microscopy, immunohistochemistry and electron microscopy.

The processing of the renal biopsy is complex and requires the support of a fully equipped anatomic pathology laboratory. Technical expertise is required to process the small fragments of tissue and to produce sections of highest quality. The correct diagnosis requires a well-trained renal pathologist with thorough knowledge of not only renal pathology but also renal medicine in order to correlate intricate tissue-derived information with detailed clinical data.

In view of the importance and consequences of the pathologic diagnosis, the Renal Pathology Society appointed an Ad Hoc Committee on Practice Guidelines, to define the essential ingredients necessary to provide quality renal pathology diagnoses. This document incorporates the consensus opinions of the committee and the RPS membership at large.
Renal failure due to acute nephrocalcinosis following oral sodium phosphate bowel cleansing.

Markowitz GS, Nasr SH, Klein P, Anderson H, Stack JI, Alterman L, Price B, Radhakrishnan J, D'agati VD.
Hum Pathol. 2004 Jun;35(6):675-84. Abstract quote  

Nephrocalcinosis is a chronic tubulointerstitial nephropathy characterized by tubular calcium phosphate deposition and slowly progressive renal insufficiency.

We report a novel association of acute nephrocalcinosis and acute renal failure (ARF) with colonoscopy preceded by a bowel-cleansing regimen consisting of oral sodium phosphate solution (OSPS). A cohort of 5 patients (mean age, 69.2 years) had normal renal function (mean serum creatininem 0.9 mg/dL) before colonoscopy and presented with ARF (mean serum creatinine, 4.9 mg/dL) from 3 days to 2 months postcolonoscopy. Past medical history included hypertension in all 5 patients. Medications included an angiotensin-converting enzyme (ACE) inhibitor (ACE-I) or angiotensin receptor blocker (ARB) in 4 patients and diuretics in 2 patients. In all patients, colonoscopy was preceded by bowel cleansing with OSPS; OSPS was contraindicated in a single patient with hyperparathyroidism and was used at excessive doses in another. Renal biopsy specimens obtained from all 5 patients revealed diffuse tubular injury and abundant tubular deposition of calcium phosphate. Although the tubular injury involved all tubular segments, lectin and immunohistochemical staining disclosed calcium phosphate deposition confined to distal tubules and collecting ducts. At a mean of 5.8 weeks of postbiopsy follow-up, renal function was unchanged in 4 patients and mildly improved in 1 patient.

We conclude that acute nephrocalcinosis is a seemingly rare complication of bowel cleansing with OSPS. The pathophysiology of acute nephrocalcinosis after treatment with OSPS likely involves transient hyperphosphatemia; volume depletion exacerbated by intercurrent ACE-I, ARB, and diuretic use; and elevated distal tubular phosphate and calcium concentrations. Greater awareness of this entity is needed to identify potential risk factors.

Epithelial differentiation of the lower urinary tract with recognition of the minor prostatic glands.

Cohen RJ, Garrett K, Golding JL, Thomas RB, McNeal JE.

Uropath Pty Ltd Perth and Perth Urology, Western Australia; and the Department of Urology, Stanford University, CA.


Hum Pathol 2002 Sep;33(9):905-9 Abstract quote

Preservation of tissues in glutaraldehyde-based fixatives allows identification of prostatic glandular secretions without resorting to immunostaining. This has enabled detailed histological assessment of the entire male urethra and bladder and has confirmed prostatic epithelial cells outside the confines of the prostate gland.

Male and female lower urinary tracts are also compared. Three intact bladders and penile urethras from radical surgical specimens, tissue from 10 radical prostatectomies, 12 penile urethral biopsy specimens, and 40 samples of of metaplastic bladder mucosa were evaluated after undergoing glutaraldehyde-based fixation (Solufix, Tissugen, Western Australia). All sections were immunostained for prostate-specific antigen (PSA) and high molecular-weight cytokeratin. Selected formalin-fixed samples also were assessed and stained for androgen receptor status, and 10 female control subjects also were evaluated. Prostatic epithelial cells, as recognized by their content of prostate secretory granules (PSG), were identified in almost all periurethral glands seen along the length of the penile urethra. These "minor prostatic glands" were composed entirely of prostatic cells or, more commonly, mixed prostatic and mucinous epithelium. The penile urethra was lined by transitional epithelium, whereas the prostatic urethra was lined by glandular cells with superficial androgen receptor-positive cells that had lost much of their secretory function. Foci of cystitis cystica/glandularis contained prostatic cells in more than half of the cases evaluated, and in all cases PSG secretion in extraprostatic sites was commensurate with PSA secretion. No prostatic secretion was seen in the female control cases, and the female urethra, in contrast to the male urethra, was lined entirely by glycogenated stratified squamous epithelium similar to the epithelium lining the vagina and vulva.

This study defines the entity of minor prostatic glands and confirms their extensive normal distribution in the adult male subject. Minimal but persistently elevated levels of serum PSA occuring after successful radical prostatectomy may be related in part to this phenomenon. The female lower urinary tract differs considerably from the male but has similar features related to the lower genital tract.

Smooth Muscle Neoplasms of the Urinary Bladder
A Clinicopathologic Comparison of Leiomyoma and Leiomyosarcoma

Scott A. Martin, M.D.; Donald L. Sears, M.D.; Thomas J. Sebo, M.D., Ph.D.; Christine M. Lohse, B.S.; John C. Cheville, M.D.

From the Departments of Pathology and Laboratory Medicine (S.A.M., T.J.S., J.C.C.) and Health Sciences Research (C.M.L.), Mayo Clinic, Rochester, Minnesota, and the Department of Pathology (D.L.S.), Northside Hospital, Atlanta, Georgia, U.S.A.


Am J Surg Pathol 2002;26:292-300 Abstract quote

We report the clinicopathologic, immunohistochemical, and DNA ploidy findings of 18 leiomyosarcomas of the urinary bladder. In addition, we compare these malignant smooth muscle tumors with 10 cases of urinary bladder leiomyoma.

The 14 male and four female patients with leiomyosarcoma ranged in age from 25 to 88 years (mean 64 years). The tumors ranged from 3.0 to 15.0 cm (mean 7.1 cm) in greatest dimension and were moderately to highly cellular, consisting of interlacing fascicles of spindled cells with mild to marked nuclear atypia. Coagulative tumor necrosis was identified in 14 cases (78%), and mitotic activity ranged from 1 to 42 mitotic figures (MF) per 10 high power fields (HPF) (mean 12 MF/10 HPF). Tumors were classified as either high-grade (12 cases) or low-grade (six cases) based on nuclear atypia, mitotic activity, and tumor necrosis. Actin positivity was present in 15 tumors (83%), and desmin immunoreactivity was present in seven tumors (39%). All cases were negative for epithelial markers and S-100. Proliferative activity, as assessed by MIB-1 staining, ranged from 0.1% to 51.4% (median 9.1%). Seven (39%) of the leiomyosarcomas were DNA aneuploid, eight (44%) were tetraploid, and three (17%) were diploid. Five patients underwent radical cystoprostatectomy, one radical cystectomy, seven had partial cystectomy, two underwent pelvic exenteration, and three patients had transurethral resection only. Follow-up information was available on all 18 cases and ranged from 2 to 68 months (mean 22 months). Of the 12 patients with high-grade tumors, six (50%) died of disease from 2 to 20 months (mean 7 months) after diagnosis and three patients (25%) are alive with metastatic tumor. Two of the six patients with low-grade leiomyosarcoma died of tumor, 61 and 68 months after diagnosis. There were five male and five female patients with leiomyoma ranging in age from 22 to 78 years (mean 61 years). The tumors ranged from 0.5 to 4.5 cm (mean 1.6 cm) in greatest dimension, were well circumscribed, and had low cellularity. Mitotic activity, necrosis, and cellular atypia were absent, and the tumors were strongly positive for both actin and desmin. MIB-1 staining ranged from 0% to 3.8% (median 0.8%). Seven (87.5%) of the leiomyomas were DNA diploid or near-diploid and one (12.5%) was DNA aneuploid. Six patients were treated with transurethral resection and four with partial cystectomy. All 10 patients were alive at the last follow-up (mean follow-up 75 months), and no tumor recurred or metastasized.

Our study shows that low-grade leiomyosarcomas are capable of malignant behavior, and high-grade leiomyosarcomas appear to behave more aggressively than low-grade tumors. In addition, the diagnosis of urinary bladder leiomyoma should be reserved for noninfiltrative smooth muscle tumors lacking mitotic activity, cytologic atypia, and necrosis.


Arcuate and interlobular phlebitis in renal allografts

Michael Torbenson, MD and Parmjeet Randhawa, MD

Hum Pathol 2002;32:1388-1391. Abstract quote

Intimal arteritis in the renal allograft has a well-documented adverse effect on graft outcome. In contrast, venulitis is currently considered an innocuous finding, based largely on observations of thin-walled intermediary venules. Arcuate and interlobular veins have not been studied specifically. These veins have well-developed muscular walls, and inflammation at this level (phlebitis) could significantly alter renal hemodynamics.

We studied the clinicopathologic correlates of arcuate and interlobular phlebitis in 31 renal allograft biopsy specimens. Phlebitis was seen in conjunction with borderline changes suggestive of acute cellular rejection (13 cases), or acute rejection Banff grade 1A (7 cases), Banff grade 1B (6 cases), Banff grade 2A (4 cases), and Banff grade 2B (1 case). Clinical follow-up (average 323 ± 460 days) showed no adverse effects of phlebitis as judged by temporal changes in serum creatinine and the grade of chronic allograft nephropathy in follow-up biopsies.

Thus it appears that arcuate and interlobular phlebitis in allograft biopsy specimens does not add prognostic information beyond that provided by conventional Banff criteria. However, this lesion frequently coexists with changes suggestive or diagnostic of acute cellular rejection, and intimal arteritis may be seen concurrently in up to 16% of cases.

T-cell/periodic acid-schiff stain: A useful tool in the evaluation of tubulointerstitial infiltrates as a component of renal allograft rejection.

Resch L, Yu W, Fraser RB, Lawen JG, Acott PD, Crocker JF, Wright JR Jr.

Departments of Pathology, Urology, Pediatrics, Biomedical Engineering, and Surgery, IWK Health Centre and Dalhousie University Faculty of Medicine, Halifax, Nova Scotia, Canada.

Ann Diagn Pathol 2002 Apr;6(2):122-4 Abstract quote

Distinguishing between tubulitis and tubulointerstitial mononuclear cell infiltrates and determining the severity of tubulitis are critical components of diagnosing and grading renal allograft rejection using the 1993 Banff schema, the revised 1997 Banff schema, or the Cooperative Clinical Trials in Transplantation grading system.

We describe a novel staining method, the T-PAS stain (CD3 and periodic acid-Schiff), which removes some of the subjectivity in the evaluation of tubulointerstitial infiltrates in renal allograft biopsies. The method simply combines two routine stains, immunoperoxidase staining for T cells (CD3) and periodic acid-Schiff (PAS) staining for tubular basement membrane, on the same section.

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Basic Principles of Disease
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Last Updated June 6, 2005

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