Tuberous Sclerosis

Scenarios: Rash, headaches, fits, shortness of breath, difficult to treat blood pressure, poor progress at school or college.

Questions to ask:

  • When did the rash start, how has it changed since then, where on your body does it affect?
  • Any headaches, weakness, numbness, tingling, fits, funny turns, changes in your vision, hearing, speech or swallowing?
  • Any shortness of breath or cough?
  • Any problems passing urine, any blood in the urine, and abdominal swelling, has anyone told you that you have problems with high blood pressure or your kidneys?
  • Any other medical problems that you see a doctor for, any operations in the past?
  • Are you on any medications? Any allergies?
  • Anyone else in the family with a rash or similar problems to these, any other medical problems that run in the family?
  • Who’s at home with you, what do you do for work?
  • How old were you when you left school, how did you do in exams, did you go to college or university?
  • Do you smoke, ever smoked, drink alcohol, or take recreational drugs?
  • How is your mood?
  • Do you have any particular worries or questions for me?

Systems to examine: For this routine get the patient on the couch, ideally with their top off, start with the hands out straight for tremor and nail changes, then scan up the arms for a fistula and check the blood pressure, examine the facial rash, look in the mouth at the palate and gums, check the neck for scars, scan the thorax for ash leaf macules, look for scars of peritoneal dialysis and transplant, ballot the kidneys, sit them forward, check for nephrectomy scars, listen to the lungs and finish at the heart and fundoscopy if you have time.

  •  Cutaneous: Peri-ungual fibromas on the nails (look at nails and toenails), adenoma sebaceum (facial angiofibromas) on the face, ash leaf macule on the thorax (ask to inspect these under Woods lamp as the depigmented macule will fluoresce), shagreen patches over the lumbar region.
  • Fundoscopy: Retinal phakomas (grey/white/yellow patches).
  • Renal: Look for tremor, check for AV fistulas, check gums for hypertrophy (could be cyclosporin for the transplant or phenytoin from the epilepsy) and at the same time look at the hard palate as a high arched palate is seen in tuberous sclerosis, neck scars (lines, parathyroidectomy), nephrectomy scars, peritoneal dialysis scars, renal transplant, ballotable kidneys due to renal angiomyolipomas or cysts.
  • Cardiac: Rhabdomyomas may cause audible murmurs due to turbulent flow across them.
  • Neurological: Brief neurological examination to asses for focal neurology if reported by the patient.

Differentials to exclude:

  • Neurofibromatosis type 1: Cafe au lait spots, neurofibromas, axillary freckling, lisch nodules.
  • Von Hippel Lindau: Cysts in the kidneys, pancreas, liver and epididymis; cerebellar haemangioblastomas, retinal angiomas, risk of phaeochromocytoma and renal cell cancer.

Investigations:

  • Bedside tests: Woods lamp (to highlight the ash leaf macules), blood pressure (hypertension), electrocardiogram (conduction blocks, Wolff Parkinsons white, hypertrophy due to outflow tract obstruction), urine dipstick (haematuria), oxygen saturations (cystic lung disease).
  • Bloods: FBC (anaemia due to haematuria), U&Es (due to renal cysts and angiomyolipomas).
  • Imaging: Plain films of the skull (railroad track calcification), MRI brain (tubers and subependymal nodules, lesions may calcify), echocardiogram (rhabdomyomas), renal tract USS/MRI (angiomyolipomas, renal cysts), CT chest (lymphangioleiomyomatosis, pneumothorax, chylous pleural effusions).
  • Special tests: Spirometry (if lung involvement).

Management:

  • Non-pharmacological: Educate on the diagnosis and give supplementary written information, focus on the familial element with a 50% risk of transmission to children and the increased risk of epilepsy; utilise all relevant members of the MDT including neurologist, epilepsy specialist nurse, general practitioner, genetic counsellor and nephrologists, if they have epilepsy give the relevant advice regarding DVLA notification and safety tips for day to day life (showers not baths, leave the door open, don’t swim unaccompanied, avoid heights like scaffolding).
  • Medical: Treat co-morbidities like epilepsy and renal disease.
  • Surgical: Renal transplant, excision of large lesions, arterial embolisation of bleeding angiomyolipomata.

Questions:

  1. What is the mode of inheritance of tuberous sclerosis? Autosomal dominant but with variable penetrance, due to defects of chromosome 9 in TSC 1 (hamartin), and chromosome 16 in TSC 2 (tuberin).
  2. Why do patients with tuberous sclerosis develop renal cystic disease? The TSC 2 gene lies next to the ADPKD 1 gene on chromosome 16 and as such they can develop manifestations of both conditions.
  3. What renal complications can these individuals develop? Renal cysts and angiomyolipomas, cyst infection, cyst bleed, cyst rupture, renal failure, renal cell carcinoma (unlike in ADPCKD, both TS and especially VHL carry a high risk of RCC).

References:

  • Radiopedia.org tuberous sclerosis – http://radiopaedia.org/articles/tuberous-sclerosis

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