Routine Excision, Rare Diagnosis: Solitary Neurofibroma Prompting NF1 Screening in an Adolescent

Abstract: A solitary plexiform neurofibroma in a 15-year-old girl prompted an unexpected referral for neurofibromatosis type 1 (NF1) evaluation. Initially excised under the impression of a lipoma, the lesion’s histopathology revealed neural origin features with strong S100 and CD34 positivity. Dermatologic examination uncovered multiple café-au-lait macules, and subsequent referral to neurology raised clinical suspicion for NF1. This case emphasizes how incidental histological findings in a benign-appearing lesion can serve as the first clinical clue of a genetic disorder, triggering appropriate multidisciplinary evaluation. Plain Language Summary: A 15-year-old girl had a small, soft lump on her upper back that looked like a harmless fatty growth (lipoma). After removing it through a minor surgery, doctors found that it was actually a type of nerve tumor called a neurofibroma. This discovery led to further evaluations that showed she might have a genetic condition called neurofibromatosis type 1 (NF1), even though she had no other obvious symptoms. This case shows how something that seems simple can be the first clue to a bigger health issue and why it’s important to look deeper when the results are unexpected. Keywords: neurofibromatosis type 1, plexiform neurofibroma, solitary neurofibroma, genetic screening, adolescent, histopathology