Tuberous Sclerosis - Diagnosis

Diagnosis

There are no pathognomonic clinical signs for tuberous sclerosis. Many signs are present in individuals who are healthy (although rarely), or who have another disease. A combination of signs, classified as major or minor, is required in order to establish a clinical diagnosis.

Diagnostic Criteria for Tuberous Sclerosis Complex
Major Features
Location Sign Onset Note
1 Head Facial angiofibromas or forehead plaque Infant – adult
2 Fingers and toes Nontraumatic ungual or periungual fibroma Adolescent – adult
3 Skin Hypomelanotic macules Infant – child More than three.
4 Skin Shagreen patch (connective tissue nevus) Child
5 Brain Cortical tuber Fetus
6 Brain Subependymal nodule Child – adolescent
7 Brain Subependymal giant cell astrocytoma Child – adolescent
8 Eyes Multiple retinal nodular hamartomas Infant
9 Heart Cardiac rhabdomyoma Fetus Single or multiple.
10 Lungs Lymphangioleiomyomatosis Adolescent – adult
11 Kidneys Renal angiomyolipoma Child – adult 10 and 11 together count as one major feature.
Minor Features
Location Sign Note
12 Teeth Multiple randomly distributed pits in dental enamel
13 Rectum Hamartomatous rectal polyps Histologic confirmation is suggested.
14 Bones Bone cysts
15 Brain Cerebral white-matter "migration tracts" Radiographic confirmation is sufficient. 5 and 15 together count as one major feature.
16 Gums Gingival fibromas
17 Liver, spleen and other organs Nonrenal hamartoma Histologic confirmation is suggested.
18 Eyes Retinal achromic patch
19 Skin "Confetti" skin lesions
20 Kidneys Multiple renal cysts Histologic confirmation is suggested.

In infants, the first clue is often the presence of seizures, delayed development or white patches on the skin. A full clinical diagnosis involves

  • Taking a personal and family history.
  • Examining the skin under a Wood's lamp (hypomelanotic macules), the fingers and toes (ungual fibroma), the face (angiofibromas) and the mouth (dental pits and gingival fibromas).
  • Cranial imaging with non enhanced CT or, preferably, MRI (cortical tubers and subependymal nodules).
  • Renal ultrasound (angiomyolipoma or cysts).
  • An echocardiogram in infants (rhabdomyoma).
  • Fundoscopy (retinal nodular hamartomas or achromic patch).

The various signs are then marked against the diagnostic criteria to produce a level of diagnostic certainty:

  • Definite – Either two major features or one major feature plus two minor features.
  • Probable – One major plus one minor feature.
  • Suspect – Either one major feature or two or more minor features.

Due to the wide variety of mutations leading to TSC, there are no simple genetic tests available to identify new cases. Nor are there any biochemical markers for the gene defects. However, once a person has been clinically diagnosed, the genetic mutation can usually be found. The search is time-consuming and has a 15% failure rate, which is thought to be due to somatic mosaicism. If successful, this information can be used to identify affected family members, including prenatal diagnosis. As of 2006, preimplantation diagnosis is not widely available.

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