Kidney And Urinary Tract Pathology Part Ii

Dysuria, urinary frequency, urgency, and suprapubic pain; systemic signs (e.g. fever) are usually absent

1. Urinalysis - cloudy urine with > 10 WBCs/high power field
2. Dipstick - positive leukocyte esterase (due to pyurina) and nitrites (bacteria convert nitrates to nitrites)
3. Culture - greater than 100,000 colony forming units (gold standard)

1. E coli (80%)
2. Staph. saprophyticus (increased incidence in sexually active young women)
3. Klebsiella pneumoniae
4. Proteus mirabilis - alkaline urine with ammonia scent
5. Enterococcus faecalis

• The presence of pyuria (>10 WBCs/hpf and leukocyte esterase) with a negative urine culture
• Suggests urethritis due to Chlamydia trachomatis or Neisseria gonorrhoeae

• Kidney infection, usually due to ascending infection
• Increased risk with vesicoureteral reflux
• Presents with fever, flank pain, WBC casts, and leukocytosis in addition to symptoms of cystitis

• E coli (90%)
• Enterococcus faecalis
• Klebsiella

• Interstitial fibrosis and atrophy of tubules due to multiple bouts of acute pyelonephritis
• Due to vesicoureteral reflux (children) or obstruction (e.g. BPH or cervical carcinoma)

• Leads to cortical scarring with blunted calyces; scarring at upper and lower poles in characteristic of vesicoureteral reflux
• Atrophic tubules containing eosinophilic proteinaceous material resemble thyroid follicles ('thyroidization' of the kidney)
• Waxy casts may be found in urine

Precipitation of a urinary solute as a stone

High concentration of solute in urinary filtrate and low urine volume

Colicky pain with hematuria and unilateral flank tenderness (stone is usually passed within hours; if not, surgical intervention may be required)

Calcium oxalate and/or calcium phosphate

• Idiopathic hypercalciuria is most common
• Hypercalcemia and its related causes must be excluded
• Also seen with Crohn disease
• TX: hydrochlorothiazide (calcium sparring diuretic)

Ammonium magnesium phosphate

• Most common: infection with urease-positive organisms (e.g. Proteus vulgaris or Klebsiella)
• Alkaline urine leads to formation of stone

Classically, results in stag horn calculi in renal calyces, which act as a nidus for UTIs; treatment involves surgical removal of stone (due to size) and eradication of pathogen (to prevent recurrence)

Uric acid

• Hot, arid climates, low urine volume, and acidic pH
• Most common stone seen in patients with gout
• Hyperuricemia (eg in leukemia or myeloproliferative disorders) increases risk

Involves hydration and alkalization of urine (potassium bicarbonate); allopurinol is also administered in patients with gout

Children

Cystinuria (a genetic defect of tubules that results in decreased reabsorption of cysteine)

Hydration and alkalization of urine

• May result from glomerulus, tubular, inflammatory, or vascular insults
• Most common causes are diabetes mellitus, HTN, and glomerular disease

1. Uremia
2. Salt and water retention leading to HTN
3. Hyperkalemia with metabolic acidosis
4. Anemia due to decreased EPO (produced by renal peritubular interstitial cells)
5. Hypocalcemia due to decreased 1-alpha-hydroxylation of vitamins D by proximal renal tubule cells and hyperphosphatemia
6. Renal osteodystrophy due to secondary hyperparathyroidism, osteomalacia, and osteoporosis

Dialysis or renal transplant; cysts often develop within shrunken end-stage kidneys during dialysis, increasing risk for renal cell carcinoma

Increased nitrogenous waste products in blood (azotemia) result in nausea, anorexia, pericarditis, platelet dysfunction, encephalopathy with asterixis, and deposition of urea crystals in skin

Hamartoma comprised of blood vessels, smooth muscle, and adipose tissue; increased frequency in tuberous sclerosis

Malignant epithelial tumor arising from kidney tubules; tumors may be hereditary or sporadic

With classic triad of hematuria, palpable mass, and flank pain

• All three rarely occur together (hematuria is most common)
• Fever, weight loss, or paraneoplastic syndrome (e.g. EPO, renin, PTHrP, or ACTH) may also be present
• Rarely presents with left-sided varicocele

Yellow mass; microscopically, the most common variant exhibits clear cytoplasm (clear cell type)

Involves loss of VHL (3p) tumor suppressor gene, which leads to increased IGF-1 (promotes growth) and increased HIF transcription factor (increases VEGF and PDGF)

Classically arise in adult males (avg. age is 60) as a single tumor in the upper pole of the kidney; major risk factor for sporadic tumors is cigarette smoke

Arise in younger adults and are often bilateral

• Von Hippel-Lindau disease is an autosomal dominant disorder associated with inactivation of the VHL gene leading to increased risk for hemangioblastoma of the cerebellum and renal cell carcinoma

based on size and involvement of renal vein (occurs commonly and increases risk of hematogenous spread to lungs and bone)

Retroperitoneal lymph nodes

• Malignant kidney tumor comprised of blastema (immature kidney mesenchyme), primitive glomeruli and tubules, and stromal cells
• Most common malignant renal tumor in children; avg. age is 3

Large, unilateral flank mass with hematuria and HTN (due to renin secretion)

• WAGR syndrome
• Denys-Drash syndrome
• Beckwith-Wiedemann syndrome

• Wilms tumor
• Aniridia
• Genital abnormalities
• and mental and motor Retardation
• associated with deletion of WT1 tumor suppressor gene (located at 11p13)

• Wilms tumor
• Progressive (glomerular) disease
• Male pseudohermaphroditism
• Associated with mutations in WT1

• Wilms tumor
• Neonatal hypoglycemia
• Muscular hemihypertrophy
• Organomegaly (including tongue)
• Associated with mutations in WT2 gene cluster (imprinted genes at 11p15.5), particularly IGF-2

• Malignant tumor arising from the urothelial lining of the renal pelvis, ureter, bladder, or urethra
• Most common type of lower UT cancer; usually arises in the bladder

Cigarette smoke; additional risk factors are naphthylamine, azo dyes, and long-term cyclophosphamide or phenacetin use

Generally seen in older adults; presents with painless hematuria

Tumors are often multifocal and recur

1. Flat - develops as a high-grade flat tumor and then invades; associated with early p53 mutations

2. Papillary - develops as a low-grade papillary tumor that progresses to a high- grade papillary tumor and then invades; not associated with early p53 mutations

• Malignant proliferation of squamous cells, usually involving bladder
• Arises in background of squamous metaplasia (normal bladder surface not lined by squamous epithelium)

• Chronic cystitis (older woman)
• Schistosoma hematobium infection (Egyptian male)
• Long-standing nephrolithiasis

Malignant proliferation of glands, usually involving bladder

From a urachal remnant (tumor develops at the dome of bladder), cystitis glandularis, or exstrophy (congenital failure to form caudal portion of the anterior abdo and bladder walls)