ANATPATH - DM

Question 1

Name an acute metabolic complication of diabetes (1)

Answer 1

Hyperosmolar, hyperglycaemic non-ketotic coma

Question 2

Name two (2) organisms to which diabetics are particularly prone (1)

Answer 2

Pyogenic organisms (e.g. Strep pneumonia, Staph aureus), TB, Clostridium perfringens, Candida

Question 3

Outline why a diabetic patient would be at risk for pyelonephritis and TB

Answer 3

Pyelonephritis (1) Sugar in urine - culture media for organisms

Tuberculosis (1) Function of inflammatory cells compromised

Question 4

List four (4) chronic complications of diabetes (2)

Answer 4

Nephropathy, Neuropathy, Accelerated atherosclerosis, Myocardial infarctions, Diabetic foot/ gangrene, Infections, mainly of skin/ kidney (pyelonephritis)

Question 5

Briefly outline the possible major long-term (pathological) cardiovascular/ vascular complications of diabetes mellitus (12)/ Name two major classes of vascular complication in DM [½ each] and give one example for each of them [2] [3] (Super NB)

Answer 5

 Macrovascular complications: Accelerated Atherosclerosis, with any mixture of:
o Coronary artery involvement  ischaemic heart disease/ myocardial infarction
o Carotid/cerebral artery involvement  ischaemic “stroke”/ cerebral infarction (CVA)
o Peripheral (especially lower limb) artery involvement  peripheral vascular disease (claudication/gangrene)
o Aneurysm formation/rupture - Especially abdominal aorta
o Atherothrombotic embolisation with resultant infarction in the relevant arterial territory.
 Microvascular complications
o Glomerulopathy (Kimelstiehl-Wilson kidney)/Renal failure
o Retinopathy (/cataracts) leading to blindness

Question 6

List two (2)/ four (4) macrovascular complications of uncontrolled diabetes (2-4)

Answer 6

Accelerated atherosclerosis leading to any or all of: Coronary artery atherosclerosis, Cerebral artery atherosclerosis, Peripheral arterial atherosclerosis (especially the major lower limb arteries), Coeliac axis atherosclerosis

Question 7

Outline the likely clinical syndromes that this patient might develop as a result of each of the major macro-vascular pathological complications (of diabetes mellitus) that you mentioned in the previous question [4]

Answer 7

Coronary atherosclerosis): Ischaemic heart disease: Angina/myocardial infarction

(Cerebral atherosclerosis): Atherothrombotic cerebral infarction (“ischaemic stroke”)

(Peripheral vascular disease): Intermittent claudication: Rest-pain; Gangrene

(Coeliac atherosclerosis): Intestinal angina

Question 8

Discuss the cardiac complications seen in diabetes mellitus (2½)

Answer 8

Increased incidence of atherosclerosis (½)  Earlier onset (½), More severe (½)

Coronary atheroma (½) predisposes to risk of myocardial infarction (½)

Question 9

Give two likely explanations for her deteriorating vision [1]

Answer 9

Diabetic retinopathy (on the basis of a microangiopathy); cataracts.

Question 10

Patient has hypertension and severe atheroma, particularly affecting one renal artery. It is determined that the unilateral renal artery atheroma is the cause of his hypertension. Explain how the hypertension comes about (5)

Answer 10

Diabetes  accelerated atheroma  partial blockage of 1 renal vessel  hypotension in that kidney   renin secretion by the kidney on that side  renin-angiotensin cycle continues until BP in affected kidney normalizes. The remainder of the body becomes hypertensive.

Question 11

List four (4) renal complications of diabetes mellitus which could be diagnosed on a kidney biopsy (4)

Answer 11

Nodular glomerulosclerosis, Hyalinised efferent and afferent arterioles, Pyelonephritis, Papillary necrosis, Vacuolisation of tubules

Question 12

Explain the mechanism for microproteinuria in diabetics (1)

Answer 12

There is glycosylation of the basement membrane of the glomerulus making it more permeable to proteins.

Question 13

Explain why diabetic patient is at risk for ascending urinary tract infections (2)

Answer 13

Raised urinary sugar  culture medium for organisms ++

Obstruction of ureters from papillary necrosis

Question 14

List two (2) complications of uncontrolled diabetes involving the eye (2) (NB)

Answer 14

Diabetic retinopathy with neovascularization, Retinal haemorrhage, Glaucoma, Diabetic cataracts

Question 15

List three (3) lesions that can occur in the eye in diabetes (1½)

Answer 15

Aneurysms, cotton wool spots, haemorrhages, cataracts

Question 16

List six (6) microvascular complications of diabetes that may be encountered in the retina in longstanding diabetes (6x½ = 3)

Answer 16

Pre-proliferative changes: Thickening of BM of retinal blood vessels, Microaneurysms, Macular oedema, Exudates

Proliferative changes: Neovascularisation – neovascular membrane, Posterior vitreous detachment, Haemorrhage, Retinal detachment

Question 17

List two (2) long term complications that might occur in the leg/foot in the presence of poorly controlled diabetes (1)

Answer 17

Gangrene of the limbs due to macroangiopathy, Diabetic foot, Peripheral neuropathy

Question 18

List three (3) possible lesions which may be present to explain the pain and parasthesia in both feet. For each lesion, briefly explain its pathogenesis (4½)

Answer 18

Ischaemia due to macroangiopathy in iliofemoral arteries due to severe atheroma of these vessels

Diabetic neuropathy due to microangiopathy [thickened BM] or macroangiopathy iliofemorals [atheroma]

Early gangrene of the feet due to thromboemboli or atheromatous emboli from iliofemoral vessels

Question 19

Outline four (4) factors which are operative in the causation of the diabetic foot (4)

Answer 19

Nerve dysfunction, Thickened vascular basement membrane, Poor polymorph function (decreased intracellular glucose), Raised blood glucose, Stress/ steroids/ poor immune function

Question 20

Outline five (5) factors that contribute to the development & persistence of the ulcer on a diabetic patient’s foot (5)/ Explain why the foot ulcers have a tendency not to heal (5)

Answer 20

Diabetes  Peripheral neuropathy  decreased pain sensation  repeated trauma and damage
Macroangiopathy & Microangiopathy  poor blood flow to feet  poor healing, poor acute inflammation
Microangiopathy  poor efflux of neutrophils from vessels
Raised glucose  > proliferation of bacteria
Low glucose in polymorphs  poor intracellular killing of organisms

Question 21

Outline the factors that predispose a patient to the pathogenesis of a diabetic foot (3)

Answer 21

Sensory neuropathy resulting in traumatic injury

Macrovascular – accelerated atherosclerosis

Hyperglycaemia predisposes to infection

Question 22

Explain the mechanism of diabetic foot ulcers (4)

Answer 22

Poor blood flow to nerves in the foot  neuropathy [1]

Macroangiopathy i.e. atheroma in large vessels [femoral and iliac] [1]

Microangiopathy [thickening of basement membranes in small vessels and capillaries]

Poor function of nerves

Small episodes of trauma not felt  significant ulcers [2]

Question 23

Describe the pathogenesis of a diabetic foot (3) (NB)

Answer 23

Combination of tissue ischaemia secondary to microvascular injury (thickening of capillary basement membranes with tissue ischaemia) and neuropathic ulceration.

Superimposed infection: Superficial (cellulitis), Deep (Osteomyelitis)

Impaired wound healing and repair

Question 24

Describe the pathogenesis of a diabetic foot (5)

Answer 24

• Trauma
• Decreased flow, poor acute inflammatory response, thick BM
• Persistence of agent due to above and high blood sugar
• Poor healing because of poor flow and low intracellular glucose
• Peripheral neuropathy

Question 25

Explain the pathogenesis of the foot ulcers in a diabetic patient [3

Answer 25

A mixture of:

• (Macrovascular) Peripheral vascular disease
• (Microvascular) (Predominantly sensory) Peripheral neuropathy
• General increased susceptibility to infection of diabetics.

Question 26

Indicate the macroscopic appearances of the ulcer and the local features that would suggest the ulcer is malignant (2)

Answer 26

Raised rolled edges  Malignant ulcer.

Enlarged inguinal nodes  Metastatic squamous carcinoma