Pyelonephritis and Urinary Tract Infections

Acute Pyelonephritis and Urinary Tract Infection

• Acute pyelonephritis pathogenesis often involves ascending urinary tract infections (UTIs).
• Reflux plays a significant role and serves as a cause in ascending UTIs.
• Gram-negative coliform bacilli are responsible for >85% of cases.
• Haematogenous aetiology is much less common.

Haematogenous Acute Pyelonephritis

• Seeding of the kidney can occur in septicaemia.
• Infective endocarditis can lead to embolisation.
• Predisposing factors include kidney scars, immunosuppression, and debility.

Ascending Acute Pyelonephritis

• More common in females due to a shorter urethra, absence of prostatic fluid protective effects, trauma, and potential hormonal effects.
• Colonisation can occur in both the urethra and bladder.
• Urinary tract obstruction and stasis of urine is a risk factor.
• Vesicoureteral reflux is a risk factor.

Chronic Pyelonephritis

• Scar formation and progressive renal failure are major risks.
• Repeated acute infections are a common cause of end-stage kidney disease, especially in children.
• Sterile reflux and scarring can occur, especially with severe obstruction.

Chronic Pyelonephritis Characteristics

• Asymmetry of the kidneys can occur.
• Acute and chronic inflammation occurs.
• Thyroidisation of tubules occurs.
• Glomerular hypertrophy and secondary focal segmental glomerulosclerosis (FSGS) are possible.
• Vascular changes can occur.
• Predisposition to struvite calculi (Staghorn) is possible.
• Special forms exist with problems related to inadequate macrophage destruction of E. coli.
• Special forms include Xanthogranulomatous and Malakoplakia.

Acute Tubulo-Interstitial Nephritis (TIN)

• Most cases are drug-induced.
• Pathogenesis is usually unknown.
• Drug-induced cases are allergic or hypersensitivity reactions.
• Immune complex involvement; for example, SLE.
• Familial factors play a part. Associated with other diseases like Sjögren's syndrome and uveitis.

Drugs Causing Acute TIN

• PPIs are a common cause.
• Antibiotics such as Penicillins and Sulphonamides, and NSAID's can be causative agents.
• Molecular agents are increasingly implicated recently.
• Eosinophils are a key pathological feature.
• Acute renal failure while in the hospital can be a result.

Other Causes of TIN

• Familial causes where eosinophils are less prominent can play a part.
• Sarcoidosis can cause TIN, with granulomas usually seen.
• TIN can result in anuria.

Renal Acute Renal Failure (ARF)

• Vascular related issues

Vasculitis

• May be ANCA-associated and systemic.

Thrombotic lesions

Renal artery stenosis/thrombosis

Emboli

• Renal artery stenosis/thrombosis and Emboli, need to be B/L for Renal ARF

Thrombotic Lesions

• Must be distinguished from vasculitis.
• Seen in malignant hypertension.
• Multiple causes and associations exist.
• Causes acute and chronic renal failure, but not usually associated with haematuria. Fibrin thrombi may be present in glomeruli in Hemolytic Uraemic Syndrome (HUS).
• Swelling of glomerular endothelial cells occurs.
• Arteriole exhibiting an "onion-skin" like thrombotic lesion is organising.

Kidney Tumours

Pathology aspects normally discussed in surgery

Benign Tumours

• Angiomyolipoma arises from perivascular epithelioid cells, containing blood vessels, smooth muscle, and fat.
• Oncocytoma has pink cells, is encapsulated, and arises from cells of collecting ducts.

Malignant (Primary) Tumours

• Nephroblastoma primarily affects children.
• Carcinoma includes transitional cell and renal cell types.

Kidney and Tumours - Clinical Features

• Kidneys can be in multiple sites, with kidney tumours included.
• The kidney is the most likely primary site.
• Unusual site for metastasis, despite receiving a significant percentage (20–25%) of the cardiac output.

Renal Cell Carcinoma

• Accounts for about 90% of kidney tumours in adults.
• Typically diagnosed around the 7th decade of life.
• Males are twice more likely to have it than females.
• Aetiology includes smoking, obesity and cystic lesions.
• Related genes are found on chromosome 3.

Pathology of Renal Cell Carcinoma

• Gross appearance: yellow-orange in color, with haemorrhage, necrosis, and cystic areas often present.
• Microscopy: clear cell carcinoma is the most common type.
• Clear cell adenocarcinoma originates from proximal convoluted tubular cells.
• Renal vein invasion may occur.
• Grading relies on nuclear features.

Renal Cell Carcinoma Types

• Papillary accounts for 10-15%
• Chromosome 7/17 trisomy, loss of Y occurs
• Often multifocal
• Chromophobe accounts for 5%
• Associated with intercalated collecting duct cells
• Patients have an excellent prognosis
• Other rarer forms exist.

Renal Cell Carcinoma - Ireland

• Males: 9th most common cancer with 350 cases/year, 3.2% incidence.
• Females: 12th most common with 200 cases/year, with <2% incidence.
• 5-year survival: 44.5% in males, 53.5% in females.

Pathology of Renal Pelvis and Ureter

• Includes congenital disorders, duplex ureter.
• PUJ obstruction cause unknown.

Urothelial Carcinoma of Renal Pelvis

• Accounts for 5-10% of renal tumours.
• Similar in appearance to urothelial carcinoma of the bladder.
• Often associated with tumours/carcinoma in situ (CIS) elsewhere in the urinary tract.
• Tumours of ureter occur in older males (>70 yrs) and have a poor prognosis.

Ca Pelvis and Ureter-Staging

• T1: Invasion of basement membrane.
• T2: Invades muscularis of Ureter and pelvis.
• T3: Invades peripelvic fat/renal parenchyma/renal pelvis; invades through the wall of the ureter.
• T4: Invades adjacent organs or peri-nephric fat.

Pathology of Urinary Bladder

• Includes congenital abnormalities and persistent foetal structures.
• Cystitis can be acute (bacterial infections) or chronic (various, including sterile cystitis and Schistosomiasis).
• Also Endometriosis, Fistulae such as Chron's and bladder obstruction such as Prostate are causes
• Neoplasms, can obstruct the Urinary Bladder

Cystitis

• Bacterial infections, or worldwide Schistosomiasis is possible.
• Males are at a greater risk if they have prostate enalrgement.
• Calculi can be a risk factor.
• Females are at a greater risk if they have a short urethra.
• Diabetes mellitus and catheter are risks.

Cystitis-Path and Clinic. Features

• Neutrophil infiltration occurs.
• Oedema occurs.
• Frequency with pain (cardinal features).
• Pelvic discomfort and M.S.U features are possible.

Neoplasms of the Urinary Bladder

• Carcinomas
• Urothelial carcinoma constitute 98% of tumours
• Squamous cell carcinoma associated with Schistosomiasis
• Adenocarcinoma is present in Fistulas

Field abnormality May be present

• Carcinoma in situ, Papilloma's, and other Urothelial Carcinoma's Role of Cystoscopy, Cytology and Biopsy play a crucial role

Urothelial Carcinoma

• Common is USA and Western Europe
• Males are three times as likely to have this than Females
• Usually people that are 50-80 years old
• Exposure to:
• Aniline dyes.
• Organic chemicals.
• Smoking is another factor

Ca Incidence -Ireland

• Males. 5th common, 466/annum, 4.3%, Median age 72 y
• Females. 13th common, 193/annum <2%, Median age 72 years
• 5yr Survival- Males 69.9%, Females 64.2%