NF1 cafe-au-lait macules vs McCune-Albright and tuberous sclerosis skin findings
How to tell NF1 cafe-au-lait macules and McCune-Albright and tuberous sclerosis skin findings apart when a board question makes them look alike.
NF1 is cafe-au-lait plus neurofibromas/Lisch; McCune-Albright is cafe-au-lait plus fibrous dysplasia/endocrine; tuberous sclerosis is ash-leaf/shagreen/angiofibromas and seizures.
Side by side
NF1 causes multiple cafe-au-lait macules, axillary freckling, neurofibromas, Lisch nodules, optic glioma, and RAS pathway tumor risk.
McCune-Albright has coast-of-Maine cafe-au-lait with polyostotic fibrous dysplasia and endocrine hyperfunction; tuberous sclerosis has ash-leaf spots, shagreen patches, angiofibromas, seizures, and hamartomas.
NF1 loss increases RAS signaling and neurocutaneous tumor formation.
McCune-Albright is activating Gs mosaicism; tuberous sclerosis involves TSC1/TSC2 mTOR dysregulation.
Six or more cafe-au-lait macules, axillary freckling, neurofibromas, and Lisch nodules support NF1.
Fibrous dysplasia and precocious puberty support McCune-Albright; ash-leaf spots and cortical tubers support tuberous sclerosis.
The trap
Pigmented skin lesions overlap, so associated neurologic, bone, endocrine, and hamartoma findings separate syndromes.
The repair move
For neurocutaneous skin findings, attach the pigment clue to its systemic syndrome.
Try a free question
CoreA 7-year-old boy has 8 cafe-au-lait macules each >5 mm, axillary freckling (Crowe sign), multiple cutaneous neurofibromas, and Lisch nodules (pigmented hamartomas) of the iris. His father has similar findings. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Neurofibromatosis type 1. Neurofibromatosis type 1 (NF1) is autosomal dominant with NF1 gene mutation; diagnostic criteria include >=6 cafe-au-lait macules, neurofibromas, axillary/inguinal freckling, Lisch nodules, optic glioma, osseous lesions, and first-degree relative with NF1.
Why the other choices are tempting
- B. McCune-Albright has unilateral cafe-au-lait macules with rough 'coast of Maine' borders, polyostotic fibrous dysplasia, and precocious puberty/endocrinopathies.
- C. Tuberous sclerosis has ash-leaf macules (hypopigmented), facial angiofibromas, shagreen patches, and CNS tubers.
- D. NF2 has bilateral vestibular schwannomas, less prominent skin findings.
- E. Sturge-Weber has port-wine stain in V1 trigeminal distribution and leptomeningeal angiomas.
Flashcards
Tap a card to flip it.
What eye finding supports NF1?
Lisch nodules support NF1 when paired with cafe-au-lait macules, axillary freckling, and neurofibromas.
What white macule supports tuberous sclerosis?
Ash-leaf spots support tuberous sclerosis.
Quick answers
What is the fastest way to tell NF1 cafe-au-lait macules from McCune-Albright and tuberous sclerosis skin findings?
NF1 is cafe-au-lait plus neurofibromas/Lisch; McCune-Albright is cafe-au-lait plus fibrous dysplasia/endocrine; tuberous sclerosis is ash-leaf/shagreen/angiofibromas and seizures.
What is the key clue for NF1 cafe-au-lait macules?
NF1 causes multiple cafe-au-lait macules, axillary freckling, neurofibromas, Lisch nodules, optic glioma, and RAS pathway tumor risk.
What is the key clue for McCune-Albright and tuberous sclerosis skin findings?
McCune-Albright has coast-of-Maine cafe-au-lait with polyostotic fibrous dysplasia and endocrine hyperfunction; tuberous sclerosis has ash-leaf spots, shagreen patches, angiofibromas, seizures, and hamartomas.
What is the common trap with NF1 cafe-au-lait macules vs McCune-Albright and tuberous sclerosis skin findings?
Pigmented skin lesions overlap, so associated neurologic, bone, endocrine, and hamartoma findings separate syndromes.