Question:medium
All of the following are criteria for Neurofibromatosis type 1 EXCEPT:
All of the following are criteria for Neurofibromatosis type 1 EXCEPT:
Show Hint
One option is actually the defining lesion of NF2, not NF1.
Updated On: Jun 23, 2026
- Brain tumor
- Acoustic neuromas
- Pseudoarthrosis
- Cafe-au-lait spots
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: The trick is to separate NF1 from NF2. NF1 is the peripheral, skin-and-bone form; its diagnostic checklist includes pigmented macules, freckling, neurofibromas, Lisch nodules, optic glioma, characteristic bone dysplasia and family history.
Step 2: Test each option against that checklist. Cafe-au-lait spots are the classic pigmentary sign, pseudarthrosis is the long-bone bony criterion, and an optic nerve glioma is the central brain tumour that counts toward NF1.
Step 3: The odd one out is the acoustic (vestibular) schwannoma. Bilateral vestibular schwannomas define NF2, the central form, and have no place in the NF1 criteria. So the exception is acoustic neuromas.\[\boxed{\text{Acoustic neuromas}}\]
Step 2: Test each option against that checklist. Cafe-au-lait spots are the classic pigmentary sign, pseudarthrosis is the long-bone bony criterion, and an optic nerve glioma is the central brain tumour that counts toward NF1.
Step 3: The odd one out is the acoustic (vestibular) schwannoma. Bilateral vestibular schwannomas define NF2, the central form, and have no place in the NF1 criteria. So the exception is acoustic neuromas.\[\boxed{\text{Acoustic neuromas}}\]
Was this answer helpful?
0
