Pathology Tutorials - Disease Case Studies Flashcards
What might cause infectious endocarditis?
It may be due to heart structural abnormalities (e.g. Bicuspid aortic valve, rheumatic valve, mitral valve prolapse, prosthetic valve). It may also occur in normal valves however.
Describe subacute bacterial endocarditis.
Subacute bacterial endocarditis occurs on structurally abnormal valves.
It is caused by low virulence commensals such as strep viridans.
There is gradual valve destruction.
Thrombus forms resulting on systemic emboli and causing low grade inflammation through cytokine production.
What are the clinical effects of subacute bacterial endocarditis?
It results in small emboli leading to infarct in the brain, kidneys and spleen.
Will get splinter haemorrhages in nail beds and microhaemorrhages in retina and skin due to infarcts by embolisms immune complexes.
Results in valve incompetence due to destruction of cusps. This results in cardiac failure.
Systemically there may be fever, weight loss, malaise, anaemia, splenomegally due to cytokine generation.
Microinfarcts due to embolism can lead to a ‘flea bitten’ kidney.
Subacute bacterial endocarditis occurs in normal valves. True or false?
False. Subacute bacterial endocarditis occurs in abnormal valves.
What are the causes of acute bacterial endocarditis?
Acute bacterial endocarditis occurs on normal valves.
It is caused by virulent organisms such as staph aureus.
The virulent bacteria proliferate on the valves causing necrosis, thrombus, perforation and destruction of valve leaflets. This causes acute cardiac failure.
How severe is acute bacterial endocarditis?
It is rapidly progressive and often fatal.
How may endocarditis be diagnosed?
Clinical suspicion, Raised erythrocyte sedimentation rate, Raised white cell count, Normochromic normocytic anaemia, Blood culture, Echocardiogram.
What is extrinsic allergic alvolitis?
Extrinsic allergic alvolitis is also known as hypersensitivity pneumonitis.
It is an immune response to inhaled antigens.
It is a type III hypersensitivity response.
What type of hypersensitivity reaction is involved in extrinsic allergic alvolitis?
Type III sensitivity response.
List some of the potential causes of extrinsic allergic alvolitis.
Animal proteins (e.g. bird droppings can lead to bird fanciers lung),
Microbial agents such as farmer’s lung from actinomyces on mouldy hay, Bagassosis from actinomyces in mouldy sugar cane, Byssinosis from exposure to cotton fibres.
What are the symptoms of extrinsic allergic alvolitis?
Dyspnoea, fever and cough will occur 4-8 hours after exposure. This usually resolves after 12-14 hours.
Steroids reduce the risk of fibrosis and reduce symptoms.
Repeated exposure leads to type IV hypersensitivity response with pulmonary fibrosis, granulomas and honeycomb lung in 5% of cases.
What are some of the causes of oesophagitis?
Infections such as candida, herpes and cmv,
Ingestion of corrosives,
Reflux,
Rare causes include chron’s and TB.
What is the most common cause of chronic oesophagitis?
Reflux.
What are the causes of reflux oesophagitis?
Reflux oesophagitis is caused by reflux of gastric acid. This may be due to increased intra-abdominal pressure (e.g. overeating and pregnancy), defective cardiac sphincter, gastric surgery, smoking and alcohol, hiatus hernia, poor posture.
What are some of the complications that may result from reflux oesophagitis?
Complications of reflux oesophagitis may include peptic ulcer of the oesophagus, stricture following chronic ulceration, Barrett’s oesophagus.
What is Barrett’s oesophagus?
Barrett’s oesophagus is columnar mucosa lining the lower oesophagus caused by longstanding reflux.
Columnar gastric type mucosa replaces the stratified squamous epithelium.
Intestinal metaplasia may occur and dysplasia may develop.
Adenocarcinoma is 100X more common in Barrett’s oesophagus and therefore patients with Barrett’s need surveillance.
List some congenital and mechanical disorders of the oesophagus.
1) . Heterotrophic gastric mucosa may lead to ulcer and stricture.
2) . Atresia (congenital failure of the oesophagus to develop properly).
3) . Diverticulae (formation of pockets in the oesophagus that may result in dysphagia/swallowing problems).
4) . Hiatus hernia.
5) . Achkasia (oesophagus loses ability to move food along).
6) . Varices (dilated vessels).
What is a hiatus hernia?
A hiatus hernia is where part of the stomach herniates above the diaphragmatic orifice. Most are acquired. They lead to increased abdominal pressure. Loss of muscle tone on the diaphragm with ageing leads to regurgitation and oesophagitis.
What is achalasia?
Achalasia is caused by loss of contractility of the lower oesophagus. It is caused when the cardiac sphincter does not relax. It is commonest in middle age. The food bolus distends the lower oesophagus. The causes are unknown but the ganglion cells are reduced in the myoteric plexus. It predisposes to squamous cell carcinoma (5% incidence in achlasia). Chagas’ disease can case secondary achlasia.
What are oesophageal Varices?
Oesophageal varicies are a localised dilation of veins. They are caused by a porto-systemic shunting of blood. Cirrhosis is the commonest cause. This may cause torrential bleeding that is often fatal.
What is chronic pyelonephritis?
Chronic pyelonephritis is chronic inflammation of the renal tubules and interstitium with scarring associated with pathological involvement of the renal calyces and pelvis.
A feature of chronic pyelonephritis is nephron loss.
What is a common feature of chronic pyelonephritis?
Nephron loss.
What is the commonest cause of end stage chronic renal failure? (5-15% of cases result from this)
Chronic pyelonephritis.
What are some common causes of chronic pyelonephritis?
Reflux ,
Obstruction.
Give an overview of reflux nephropathy.
Reflux nephropathy is the commonest cause of chronic pyelonephritis. It is congenital and begins in childhood when reflux of urine from the bladder and up the ureters occurs. It leads to recurrent inflammation and scarring and usually manifests in early adulthood.
Give an overview of obstructive nephropathy.
Obstructive nephropathy is obstruction of pelvicalyceal drainage. This may be unilateral or bilateral. Obstructions may be congenital (e.g. posterior urethral valves) or may also be caused by stones or tumours.
In obstructive nephropathy what cases the renal damage?
Renal damage in obstructive nephropathy is caused by increased pressure of urine causing atrophy of renal parenchyma and may also be caused by infection.
Describe the morphology of chronic pyelonephritis.
Irregular scarring in the kidneys, Distorted calyces, Kidneys may become hydronephritic. Chronic interstitial inflammatory infiltrate and fibrosis, Atrophy of tubules, Sclerosis of glomeruli.
