Clinical scenario: Focal seizures | Skin lesions | Cortical tubers
A 2-year-old boy is referred for evaluation of recurrent focal seizures and developmental delay. His parents report that he has had several episodes of abnormal movements since infancy.
On examination:
- Multiple hypopigmented macules are seen over the trunk.
- A rough, thickened plaque is present over the lower back.
- Multiple reddish papules are present over the cheeks.
MRI brain shows:
- Multiple cortical tubers
- Subependymal nodules along the lateral ventricles
Renal ultrasound demonstrates multiple bilateral renal lesions.
Which of the following is the most likely diagnosis?
A. Sturge-Weber syndrome
B. Neurofibromatosis type 1
C. Tuberous sclerosis complex
D. Von Hippel-Lindau disease
E. Ataxia-telangiectasia
Correct answer & Explanation:
Correct Answer: C. Tuberous sclerosis complex
Explanation:
This child has tuberous sclerosis complex (TSC), an autosomal dominant neurocutaneous disorder caused by mutations in:
- TSC1 gene → hamartin
- TSC2 gene → tuberin
These mutations cause activation of the mTOR pathway, resulting in multiple hamartomatous lesions.
Key clinical features:
Skin
- Hypomelanotic macules (“ash leaf spots”)
- Facial angiofibromas
- Shagreen patch
Brain
- Cortical tubers → seizures, developmental delay
- Subependymal nodules
- Subependymal giant cell astrocytoma (SEGA)
Kidney
- Angiomyolipomas
- Renal cysts
Why the other options are incorrect
- A. Sturge-Weber syndrome: Port-wine stain in V1 distribution, leptomeningeal angioma, seizures, and tram-track cortical calcifications.
- B. Neurofibromatosis type 1: Café-au-lait spots, neurofibromas, axillary freckling, and optic pathway gliomas.
- C. Tuberous sclerosis complex: Correct — cortical tubers + hypopigmented macules + renal lesions.
- D. Von Hippel-Lindau disease: Retinal angiomas, CNS hemangioblastomas, and renal cell carcinoma; does not cause cortical tubers.
- E. Ataxia-telangiectasia: Progressive ataxia, telangiectasia, and immunodeficiency; no hamartomatous lesions.
Learning Point
Important neurocutaneous syndromes:
| Syndrome | Skin finding | CNS finding |
|---|---|---|
| Tuberous sclerosis | Ash leaf spots, angiofibromas | Cortical tubers, SEGA |
| Sturge-Weber | Port-wine stain (V1) | Leptomeningeal angioma, seizures |
| NF1 | Café-au-lait spots | Neurofibromas, optic glioma |
| NF2 | Few skin findings | Bilateral vestibular schwannomas |
