Sunday 19 September 2010

MRCP revision battle 15.1: Renal cell carcinoma

I've had a day off in which I've covered literally hundreds of miles and drank excessive amounts of tea and cider and seen far more gingham than any one person ever should.  Net result has been a restoration in my energy levels and so today is going to be a blockbuster of a set of battles, with 8 separate topics to cover including two that I'd never even heard of in my preceding 8 years of studying medicine.  So lets get started!

MRCP revision battle 15.1: Renal cell carcinoma
MRCP revision battle 15.2: Von Hippel Lindau
MRCP revision battle 15.3: Neuralgic amyotrophy
MRCP revision battle 15.4: Porphyrias
MRCP revision battle 15.5: Kearns-Sayre
MRCP revision battle 15.6: Klinefelters
MRCP revision battle 15.7: Pellegra
MRCP revision battle 15.8: Neuroleptic malignant syndrome

MRCP revision battle 15.1: Renal cell carcinoma

Renal cell carcinoma, also known as hypernephroma or Gravitz Tumour, is a cancer arising in the proximal renal tubular epithelium.

It accounts for 85-90% of primary renal cancer.

The classic triad for renal cell carcinoma is:
  1. haematuria
  2. loin pain
  3. abdominal mass
(NB: classic triads of course rarely exist, but may kindly present themselves during MRCP questions)

Renal cell carcinoma may also be linked to pyrexias of unknown origin.
Another clinical sign to look out for is left variocele - caused by invasion of the left renal vein causing compression of the left testicular vein.

Factors associated with developing renal cell carcinoma include:
  • smoking
  • middle aged males (male:female 2:1)
  • Von-Hippel Lindau syndrome (wait for the next battle if you don't know that that is)
  • tuberous sclerosis
  • acquired cystic kidney disease in renal failure

25% of patients with renal cell carcinoma have mets at presentation.  The commonest mets are bone, liver and lung.

Endo effects associated with renal cell carcinoma include:
  • erythropoietin --> polycythaemia
  • PTH --> raised calcium
  • renin --> raised BP
  • ACTH

Treatment is surgery.  If mets are present IL-2 or interferon alpha may also be considered.

There is a 45% 5 yr survival.

Now on to meet Von-Hippel-Lindau syndrome...

MRCP revision battle 15.2: Von Hippel Lindau disease

Von Hippel Lindau disease is a rare autosomal dominal condition that results in haemangioblastomas in:
  • cerebellum (may present as ataxia)
  • spinal cord
  • kidney
  • retina (may present as visual loss)

It is associated with bilateral renal cell carcinomas (develop in approximately 50% of patients with VHL) and pheochromocytomas.

For those of you who are feeling really geeky the gene responsible is on chromosome 3 and it is a mutation in a tumour supressor gene.

So after that brief acquaintance, lets move on to a condition I'd never heard of before today - neuralgic amyotrophy...

MRCP revision battle 15.3: Neuralgic amyotrophy

Neuralgic amyotrophy.  Never heard of it?  Me neither before today, so here are just a few facts to get you through MRCP...

Neuralgic amyotrophy is sometimes also known as brachial plexus neuropathy.

It has a particularly specific presentation:
  • severe pain in shoulder
  • followed by weakness and atrophy of muscles in arms

This presentation alone in an MRCP question should point you towards neuralgic amyotrophy being the answer.  Other clues which would suggest this diagnosis include:
  • preceeded by a URTI
  • decreased or absent reflexes
  • sensory abnormalities

Rarely the diaphragm may also be affected.

There is a risk of shoulder joint subluxation or winging of the scapula.

This link takes you to an image of what just basic neuralgic amyotrophy can look like.

In general it resolves spontaneously in a few months, and treatment is conservative.

After that interesting interlude, lets do battle with the porphyrias...

MRCP revision battle 15.4: Porphyrias

Porphyrias are rare genetic disorders causing abnormalities of enzymes responsible for haem synthesis, resulting in accumulation of intermittent compounds (porphobilinogen, aminolaevulinic acid) and porphyrins.

This battle will focus on 2 acute porphyrias (acute intermittent and variegate) and 1 chronic (porphyria cutanea tarda).

1. Acute intermittent porphyria

Acute intermittent porphyria is an autosomal dominant condition in which there is a defect in porphobilinogen deaminase

Females aged 20-40 are most affected.

There is always raised urinary porphobilinogen and aminolaevulinic acid, but the rise is greater during acute attacks.  The importance of these substances is that the urine goes deep red on being left.

Signs and symptoms include:
  • abdominal pain
  • hypertension
  • low sodium
  • low potassium
  • hypotonia
  • psychosis
  • paralysis
  • seizures
Note there are NO skin symptoms.

A way to remember this list is to think of a patient saying to you "oh doctor, my abdo pain is giving me high blood pressure and stopping me being able to stand (paralysis)"... to which you may think "ah yes, you are a teaspoon (tsp = low tone, sodium, potassium) of crazy (psychosis) aren't you?"

Drugs that can precipitate acute porphyria include:
  • alcohol
  • benzos
  • rifampicin
  • tetracyclines
  • phenytoin
  • OCP
  • halothane
  • sulphonamides

Treatment is:
  • remove precipitating factores
  • IV fluid to correct low sodium/potassium
  • high carb diet
  • IV haematin
  • prochlorperazine for nausea
  • other symptomatic treatment

Although a rare diagnosis, porphyria should always be a differential in someone presenting with abdominal pain.

2. Variegate porphyria

This is an autosomal dominant condition characterised by a deficit in protoporphyrin oxidase.

It can cause abdominal pain and neuro symptoms, but in contrast to acute intermittent porphyria it also has a photosensitive blistering rash.

It is commoner in South Africans (afrikaans)

3. Porphyria Cutanea Tarda

This is due to uroporphyrinogen decarboxylase deficiency.

It results in a photosensitive rash with bulla.
It is also associated with hypertrichosis.
(these two factors may be the basis of werewolf legends...)

Urine has raised uroporphyrinogen which glows pink under a Woods light

Attacks are precipitated by alcohol, iron and oestrogen.

Treatment is with chloroquine.

Wow, that was quite long.  The next battle is far shorter, and is on the second condition I'd never heard of before today...

MRCP revision battle 15.5: Kearns Sayre

Kearns Sayre is an exceptionally rare condition caused by mitochondrial DNA mutations which results in:
  • progressive external opthalmoplegia
  • pigmentary degeneration of retina
  • heart block

It may also cause proximal muscle weakness, ptosis and ataxia.
Symptoms must begin before the age of 20.

If part 2 asks what investigation you want to do, the correct answer is muscle biopsy looking for ragged red fibres.

Onwards for another brief eponymous syndrome, Klinefelters..

MRCP revision battle 15.6: Klinefelters

Klinefelters is the commonest sex chromosome disorder, affecting roughly 1 in 1000 men.

Its karyotype is 47 XXY

The key features are:
  • tall stature
  • small testes
  • azoospermia
  • gynaecomastia

 Bloods show:
  • low testosterone
  • high LH/FSH

Treatment is with testosterone

Note there is increased risk of OP and breast cancer.

So on to the penultimate battle of the day, pellegra...

MRCP revision battle 15.7: Pellegra

Pellegra is nicotinic acid deficiency = vitamin B3 deficiency.

Symptoms include:
  • diarrhoea
  • dementia
  • dermatitis
  • depression
  • ataxia
  • insomnia
(remember as in a 4d)

Causes of pellegra include:
  • alcoholism
  • diet
  • isoniazid
  • carcinoid syndrome

And we're finally about to embark on the last battle of this epic day, neuroleptic malignant syndrome...

MRCP revision battle 15.8: Neuroleptic malignant syndrome

Neuroleptic malignant syndrome is a condition that can complicate antipsychotic use. 

Its features are:
  • pyrexia
  • rigidity
  • tachycardia

Bloods show:
  • raised CK
  • leucocytosis
  • acidosis

It is commonest in young males, and onset is usually in the first 10 days of taking the drug or after the dose has been increased.

It is important not to miss as it has a 10% mortality.

Treatment is to stop the antipsychotic, give IV fluids, dantrolene and ?bromocriptine.

That's all for today, I'll catch up on the 'wars' tomorrow after I've caught up on sleep!