Diagnostic Approach for Segmental Neurofibromatosis Type 1

Clinical Diagnostic Criteria

• Document ≥6 café-au-lait macules measuring ≥5mm (prepubertal) or ≥15mm (postpubertal) within the affected body region, as recommended by the National Institutes of Health, to diagnose segmental NF1 1
• Examine for freckling limited to the axillary or inguinal region on the affected side, as part of the diagnostic criteria for segmental NF1 1

Imaging Evaluation

• MRI is preferred over CT to assess the full extent of neurofibromas and avoid ionizing radiation exposure, according to the Genetics in Medicine guidelines 2
• Evaluate for plexiform neurofibromas if subcutaneous masses extend beyond superficial tissue, as suggested by the Genetics in Medicine guidelines 2

Clinical Pitfalls to Avoid

• Monitor for rapid growth or pain in existing neurofibromas, as concern for malignant transformation, although the risk is lower than in generalized NF1, as noted in the Genetics in Medicine guidelines 2

Surveillance Recommendations

• Annual clinical examination of the affected body region is recommended, including assessment for new or changing neurofibromas, as suggested by the Genetics in Medicine guidelines 2