1. Tubular & interstitial diseases
Kidney pathology
Tubular & interstitial diseases

2. Kidney - cut surface * * Outer cortex (Co)
Inner medulla composed of pyramids *
Cortical columns of Bertini (B) between pyramids*
Urine first collects in calyces, pelvis Co * * B
Calyx
Pelvis

3. Malpighi and Malpighian “corpuscles” (glomeruli)

4. Glomerular structure Arterioles Capillaries
Mesangium (“between capillaries”)
Urinary space surrounds glomerulus within Bowman’s capsule
Urin sp -> prox tubule

5. Normal renal tubules

6. Acute pyelonephritis Most severe end of spectrum of UTI
Acute bacterial inflammation of kidney
E coli, Proteus, Enterobacter, Klebsiella …
Abscesses in cortex, medulla
Polymorphs in tubules; glomeruli spared
(CMV, polyoma virus in immunocompromised)

7. Acute pyelonephritis

8. Acute pyelonephritis

9. Acute pyelonephritis - clinical
M < 1yr and over 40 yrs; F yrs
Sudden onset tenderness in costo-phrenic angle
Temp, rigors, cystitis
Most resolve quickly
May recur, become chronic
Complications

10. Pathogenesis of acute pyelonephritis
(Haematogenous spread)
Bacterial adhesins, colonisation, ascending infection
Cystitis
Vesico-Ureteric Reflux & Intrarenal Reflux, congenital or acquired
VUR: Urine, bacteria -> ureter
Inrarenal reflux: Urine enters kidney papillae

11. Predisposing factors Short female urethra
Obstruction (pregnancy, congenital, stones, tumours, BPH)
Bladder dysfunction
Diabetes
Catheters, cystoscopy, other
Vesico-Ureteric Reflux & Intrarenal Reflux
If no reflux, infection only in bladder

12. Complications of Acute Pyelo
Perinephric abscess
Pyonephrosis
*Papillary necrosis
Fibrous scars, chronic pyelonephritis

13. Chronic pyelonephritis
Scars overlying distended calyces
Chronic inflammation and fibrosis involving tubules and interstitium
Two types
Reflux nephropathy
Chronic obstructive pyelonephritis

14. Reflux nephropathy Commoner VUR pressure threshold Organisms
Refluxing papillae at upper, lower poles
Hypertension at yrs

15. Chronic pyelonephritis (reflux)

16. Chronic pyelonephritis - reflux type

17. Chronic pyelonephritis, obstructive
Older patients
Strictures, calculi in ureter, renal pelvis
BPH
Tumours

18. Chronic pyelonephritis - clinical
Chronic renal failure, hypertension
UTI (but often negative urine cultures)
Interstitial fibrosis, tubular atrophy, thyroidization of tubules, thick arteries, FSGS
Accounts for % of patients on dialysis
Other types of pyelonephritis

19. TB (L) & Xanthogranulomatous PN (R)

20. Non-bacterial inflammation of renal tubules, interstitium
Drugs/toxins: penicillins, rifampicin, NSAIDs…..
Immune injury (types I, IV); direct, unknown
Fever, oliguria in 50%, rash
Micro; inflammatory cells, inc eosinophils
Analgesic nephropathy - phenacetin, +/- aspirin, codeine
Assoc with glomerular disease e.g. SLE, renal vasculitis
Gout, multiple myeloma
Renal allograft rejection

21. Acute interstitial nephritis

22. Eosinophils in drug induced interstitial nephritis

23. Acute renal transplant rejection

24. Acute renal failure Sudden onset of oliguria (<400ml)
Raised serum Creatinine
Cause determines symptoms, prognosis
Overall mortality is 40%
Drugs, toxins
Crescentic glomerulonephritis e.g. ANCA+ vasculitis
Genitourinary obstruction
Shock, ischaemia

25. Acute renal failure - pathology
Most patients have a microscopic lesion - Acute Tubular Necrosis (necrosis of tubular epithelial cells is a “marker” of acute loss of renal function)
Renal tubular epithelium sensitive to toxins, ischaemia
Vasoconstriction -> hypoxia in outer medulla
Two types of ATN:
ATN due to drugs, toxins - PCT cells (95% survival)
ATN due to ischaemia, shock or sepsis - granular casts (20-50% survival)

26. Normal tubules (L) and drug-induced ATN* (R)

27. ATN, drug-induced

28. ATN due to toxin

29. ATN due to Sepsis/Ischaemia

30. Interstitial fibrosis and tubular atrophy in chronic renal disease correlate with progressive loss of renal function

31. Chronic renal failure
Progressive and irreversible loss of renal tissue
Chronic GN, chronic PN, hypertensive nephrosclerosis, diabetes, adult type PCKD
Symptoms - anaemia, dehydration, nausea, metabolic bone disease, etc
Asymptomatic renal insufficiency present prior to this while kidneys’ intact nephrons compensate
Dialysis, transplant or death within 1 year of onset of CRF