What are the updated diagnostic criteria for tuberous sclerosis complex?

Updated Diagnostic Criteria for Tuberous Sclerosis Complex

The clinical diagnostic criteria for TSC were updated in 2021, with two key changes: (1) "multiple cortical tubers and/or radial migration lines" now specifically replaces the previous nonspecific term "cortical dysplasias," and (2) sclerotic bone lesions have been reinstated as a minor criterion after being removed in 2012 1. These updates were further referenced in 2025 guidelines 2.

Diagnostic Framework

The diagnosis of TSC operates on two levels: genetic and clinical, with only two diagnostic categories (definite or possible TSC), simplified from the previous three-tier system 1, 3.

Genetic Diagnostic Criterion (Definite TSC)

• A pathogenic variant in TSC1 or TSC2 is alone sufficient for definite diagnosis 1, 3
• This applies even without clinical manifestations
• Important caveat: 10-15% of individuals meeting clinical criteria have no identifiable germline pathogenic variant, so negative genetic testing does NOT rule out TSC in clinically symptomatic patients 2
• Some individuals are genetically mosaic for TSC1/TSC2 variants 1

Clinical Diagnostic Criteria

Definite TSC requires:

• Two major criteria, OR
• One major criterion plus ≥2 minor criteria 1, 3

Possible TSC requires:

• One major criterion, OR
• ≥2 minor criteria 1, 3

Major Criteria (Updated)

1. Hypomelanotic macules (≥3, at least 5 mm diameter)
2. Angiofibromas (≥3) or fibrous cephalic plaque
3. Ungual fibromas (≥2)
4. Shagreen patch
5. Multiple retinal hamartomas
6. Multiple cortical tubers and/or radial migration lines (this is the updated, more specific terminology replacing "cortical dysplasias") 1
7. Subependymal nodules
8. Subependymal giant cell astrocytoma (SEGA)
9. Cardiac rhabdomyoma
10. Lymphangioleiomyomatosis (LAM)
11. Angiomyolipomas (≥2 renal)

Minor Criteria (Updated)

1. "Confetti" skin lesions
2. Dental enamel pits (≥3)
3. Intraoral fibromas (≥2)
4. Retinal achromic patch
5. Multiple renal cysts
6. Nonrenal hamartomas
7. Sclerotic bone lesions (reinstated in 2021 update) 1

Clinical Pearls for Diagnosis

Early Recognition

• Hypomelanotic macules are typically the earliest cutaneous manifestation, often present in infancy, making them critical for early TSC identification 4
• Angiofibromas and hypomelanotic macules are the most frequent dermatological findings overall 4
• Cardiac rhabdomyomas may be detected on fetal echocardiography if TSC is suspected prenatally 2

Genotype-Phenotype Correlations

• TSC2 variants generally present with more severe neurological phenotype and possibly increased renal cancer risk compared to TSC1 2
• The TSC2:TSC1 pathogenic variant ratio is approximately 8:1 4
• Ungual fibromas show significant association with TSC2 pathogenic variants (10-fold greater frequency) 4
• Rare TSC2 variants (p.Arg622Trp, p.Arg905Gln, p.Ser1036Pro, p.Arg1200Trp, p.Gln1503Pro, p.Gly1579Ser, p.Arg1713His) may present with milder phenotypes 2

Key Diagnostic Pitfalls

• Do not exclude TSC based on negative genetic testing alone if clinical criteria are met—10-15% of clinically definite cases lack identifiable variants 2
• The 2021 update emphasizes specificity over sensitivity: "cortical dysplasias" was too nonspecific, hence the change to "multiple cortical tubers and/or radial migration lines" 1
• TSC manifestations develop over a lifetime with wide phenotypic variability—a single negative evaluation does not exclude future diagnosis 1, 3