Pathology of kidney Flashcards
List the macroscopic features that are observable in a normal bisected kidney
- outer cortex
- inner medulla
- renal hilum
What are the macroscopic featuers of hydronephrosis?
- no visible cortex or medulla
- resembles a “bag of water”
typically occurs secondary to renal calculi
Describe the macroscopic features of PCKD/PKD
- enlarged
- loss of architecture
note: progressive lof, could be completely functional in earlier years
Describe the structure and function of the nephron and glomerulus
The kidney is divided into structural and functional units called nephron
When diagnosing pathologies look out for four:
- glomerulus
- vessels/vasa recta
- tubules
- interstitium
The nephron can be divided into:
- asceding and descending loops of Henle
- peritubular capillaries
- proximal and distal tubules
- glomerular capullaries
- bowman’s capsule
- medulla
- renal artery and renal vein
- ureter
- cortex
- medulla
- pelvis
Describe the histology of the glomerulus
Main features include:
- capillary loops
- endothelial cells
- mesangial cells
capillary loops are indicated by presence of RBCs
Describe the filtration barrier
Consists of three main features ()
- basement membrane
- endothelium
- mesangial cells
Describe histological differences between renal cortex and medulla
- no glomerulus present in sample of medulla
Describe the main types of renal diseases
Renal diseases
can be broadly categorised into
- neoplastic
- non-neoplastic or medical renal diseases
Describe the common manifestations of medical renal disease
Someone with a medical renal disease may present with
- isolated haematuria
- isolated proteinuria
- nephritic syndorme
- nephrotic syndrome
- acute renal failure (ARF)
- chronic renal failure (CRF)
look up isolated haematuria
List the types of medical renal disease
- Glomerular: e.g. glomerulonephritis, glomerulonephropathy
Note: the majority of glomerular diseases involve immune system even if inflammatory cells cannot be seen - Tubular/interstitium or tubulointerstitial e.g. drug-induced tubulointerstitial nephritis (e.g. NSAIDs, PPIs)
- Extraglomerular vessels e.g. vasculitis, vasculopathies (diabetes, hypertensive arteriolosclerosis)
List the types of glomerulonephritis
- Primary or idiopathic - isolated to kidney: may represent immune reaction against intrinsic renal antigen
- Secondary or systemic cause: may represent immune reaction against various antigens- glomerulus may trap antigens/antibody-antigen complexes, leading to glomerulonephritis
- infections (viral/bacterial/parasitic) or post-infectious
- malignancy (Solid organ paraneoplastic or haematolymphoid, amyloidosis)
- drugs (abuse, medical) and toxins (e.g. bites)
- connective tissue disorders and autoimmunity
- systemic vasculitis
- endocrine (diabetes mellitus)
- inflammatory e.g. sarcoidosis
- pregnancy
N.B. Some glomerular diseases (glomerulopathies) are inherited or caused by unclear (inflammatory? or toxic?) mechanisms
Describe role of immune system in glomerulonephritis
- intrinsic antigen e.g. anti-GBM:
- smooth
- cell mediated immunity: T cells may release factors, even though they are sparse e.g. MCD
- trapped/extrinsic antigen “c” complexes:
- clumpy
- will deposit in different areas because of size and charge
- +/- complement consumption
Complexes can deposit in various locations
- subendothelial
- subepithelial
- mesangial
- linear immune complex deposits
- C3 deposition
Distinguish between nephritic and nephrotic syndrome
Nephritic:
- very sick patients ^[“dying”]
- decreased urine output (oliguria, anuria)
- haematuria (+/- RBC casts, and dysmorphic RBCs)
- hypertension
- variable proteinuria
Nephrotic:
- proteinuria > 3.5 g/d
- oedema
- hypoalbuminaemia
- hyperlipidaemia
- infection
- hypercoaguability
Describe syndromes linked to glomerulonephritis
Several syndromes related to GN have been described:
- nephrotic syndrome: proteinuria >3.5/d, oedema, hypoalbuminaemia, hyperlipidaemia, lipiduria
- acute nephritis/nephritic syndrome: haematuria, variable proteinuria, azotaemia (BUN, creatinine, other secondary waste products in the blood), and hypertension
- rapidly progressive glomerulonephritis: haematuria, oliguria, and acute renal failure
(see notes for recap images)
NOTE:
- minimal change disease is a paediatric disease
- mesangiocapillary GN is more present in elderly populations
Note that nephritic and nephrotic diseases can occur. In cases of IgA nephropathy, haematuria is present. No haematuria is present in membranous or mesangiocapillary GN.
Summary note on pathophysiology of nephritic vs nephrotic syndromes:
- nephritic: “blocked sieve”, hypercellular glomeruli (inflammatory cells, damaged swollen endothelial cells, formation of crescents)
- nephrotic: “leaky sieve”, normocellular glomeruli, faulty basement membrane (thin-alports, flattened podocytes- minimal change, thickened membrane - membranous), mesangial changes (deposits, sclerosis)
What is the purpose of special stains in renal pathology?
Look for fibrosis or deposition of abnormal proteins e.g. amyloids
