# Neurocutaneous Syndromes Skin Signs and Tumour Associations

> Neurocutaneous syndromes for NEET-PG Medicine: NF1 NIH criteria, NF2 schwannomas, tuberous sclerosis, Sturge-Weber and von Hippel-Lindau with key skin signs.

- Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/neurocutaneous-syndromes
- Exam / course: NEET-PG · Subject: Medicine
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-08
- Last updated: 2026-10-08
- Reference basis: Bradley's Neurology in Clinical Practice; Harrison's Principles of Internal Medicine
- How to cite: "Neurocutaneous Syndromes Skin Signs and Tumour Associations", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/neurocutaneous-syndromes

## Direct answer

Neurocutaneous syndromes are mostly inherited disorders in which tumours and malformations involve both the skin and the nervous system, most of them through tumour-suppressor gene mutations. A cutaneous sign usually identifies the syndrome: café-au-lait macules with axillary freckling suggest neurofibromatosis type 1, ash-leaf macules and facial angiofibromas suggest tuberous sclerosis, and a trigeminal port-wine stain suggests Sturge-Weber syndrome. Bilateral vestibular schwannomas mark neurofibromatosis type 2, and cerebellar haemangioblastomas with clear cell renal carcinoma mark von Hippel-Lindau disease.

## What you must remember

- **NF1 diagnosis:** two or more of seven NIH criteria, including six or more café-au-lait macules (over 5 mm before puberty, over 15 mm after), axillary or inguinal freckling and two or more Lisch nodules.
- **NF1 associations:** optic pathway glioma, phaeochromocytoma and malignant peripheral nerve sheath tumour; the gene lies on chromosome 17 and codes neurofibromin, a RAS regulator.
- **NF2 hallmark:** bilateral vestibular schwannomas on MRI, with meningiomas, ependymomas and juvenile posterior subcapsular cataract; skin signs are few, so schwannomas without café-au-lait spots point to NF2.
- **Tuberous sclerosis:** seizures (often infantile spasms), intellectual disability and facial angiofibromas, with ash-leaf macules, shagreen patch, cortical tubers and subependymal giant cell astrocytoma.
- **Cardiac rhabdomyoma:** the commonest cardiac tumour in infants and a prenatal clue to tuberous sclerosis; TSC1 lies on chromosome 9 and TSC2 on chromosome 16.
- **Sturge-Weber syndrome:** port-wine stain in the V1 or V2 territory, ipsilateral leptomeningeal angioma with gyriform "tram-track" calcification, seizures and glaucoma.
- **Von Hippel-Lindau disease:** haemangioblastomas of the cerebellum, spinal cord and retina, clear cell renal carcinoma, phaeochromocytoma and pancreatic cysts; the gene lies on chromosome 3p25.

## A worked case: seizures, a pale patch and a heart lesion

A three-month-old is brought with infantile spasms, and the echocardiogram shows a cardiac mass while the skin shows a hypopigmented macule on the trunk. Begin with the skin, which narrows the field fast.

1. **Read the skin:** An ash-leaf macule is best seen under a Wood's lamp.
2. **Link the heart:** Together with a cardiac rhabdomyoma, the ash-leaf macule makes tuberous sclerosis the working diagnosis.
3. **Image the brain:** MRI typically shows cortical tubers and subependymal nodules.
4. **Check the kidneys:** Renal ultrasonography looks for angiomyolipomas.
5. **Settle with genetics:** TSC1 or TSC2 genetic testing settles equivocal cases.

Had the child instead shown six café-au-lait macules and axillary freckling without seizures, the route would run through slit lamp examination for Lisch nodules, MRI of the optic pathways and blood pressure measurement. A 35-year-old with hearing loss and unsteadiness but few skin marks is different again: bilateral schwannomas on MRI point to NF2 and call for audiology and genetic testing.

| Feature | NF1 | NF2 |
| --- | --- | --- |
| Dominant finding | Skin change and neurofibromas | Bilateral vestibular schwannomas |
| Skin signs | Many café-au-lait macules and freckling | Few skin marks |
| Eye finding | Lisch nodules and optic pathway glioma | Juvenile posterior subcapsular cataract |

The table shows why hearing loss with multiple café-au-lait spots is a deliberate mismatch.

## Where the examiner sets the trap

Several errors recur in these vignettes.

- **Trap:** Conflating NF1 and NF2 because both are called neurofibromatosis. — **Correct:** NF1 is dominated by skin change and neurofibromas, whereas NF2 is dominated by schwannomas.
- **Trap:** Assuming seizures with facial lesions must mean tuberous sclerosis. — **Correct:** Sturge-Weber syndrome also fits, and the discriminator is the mark itself: hypopigmented ash-leaf macules with facial angiofibromas in tuberous sclerosis and a flat red port-wine stain in Sturge-Weber, with tram-track calcification on imaging.
- **Trap:** Missing systemic features in von Hippel-Lindau disease. — **Correct:** A young adult with cerebellar haemangioblastoma, erythrocytosis and a renal mass should prompt consideration of an erythropoietin-producing tumour and clear cell carcinoma.

## Frequently asked questions

### Which skin sign separates neurofibromatosis type 1 from tuberous sclerosis?

Café-au-lait macules with axillary or inguinal freckling point to neurofibromatosis type 1, while hypopigmented ash-leaf macules and facial angiofibromas point to tuberous sclerosis, which is best confirmed with brain MRI and genetic testing.

### What are the NIH diagnostic criteria for neurofibromatosis type 1?

Two or more of seven features establish the diagnosis: six or more café-au-lait macules, two or more neurofibromas or one plexiform neurofibroma, axillary or inguinal freckling, optic pathway glioma, two or more Lisch nodules, a distinctive osseous lesion, and a first-degree relative with neurofibromatosis type 1.

### Which tumour is the hallmark of neurofibromatosis type 2?

Bilateral vestibular schwannomas on MRI are the hallmark of neurofibromatosis type 2, commonly presenting in young adulthood with hearing loss, tinnitus or imbalance. Meningiomas, ependymomas and juvenile posterior subcapsular cataracts are the other recognised features of neurofibromatosis type 2.

### Which cardiac finding raises suspicion of tuberous sclerosis in a newborn?

Cardiac rhabdomyoma is the classic finding, often seen on prenatal ultrasound or neonatal echocardiography and frequently regressing with age. A rhabdomyoma in a newborn should prompt a search for skin lesions, brain tubers and renal angiomyolipomas, followed by TSC1 or TSC2 genetic testing.