## Why "Café-au-lait macules with irregular jagged ('coast of Maine') borders" is correct The irregular jagged "coast of Maine" border pattern is a hallmark of McCune-Albright syndrome, NOT neurofibromatosis type 1. NF1 café-au-lait macules are characteristically smooth-bordered and oval, described as "coast of California." This distinction is critical for differential diagnosis and appropriate surveillance counseling. The 2021 NIH Revised Diagnostic Criteria for NF1 specify smooth-bordered café-au-lait macules; irregular borders would suggest an alternative diagnosis and are not a recognized criterion for NF1. ## Why each distractor is wrong - **≥6 café-au-lait macules >5 mm in prepubertal children or >15 mm in postpubertal individuals**: This is criterion 1 of the 2021 NIH Revised Diagnostic Criteria and is a major diagnostic feature of NF1. The patient in the vignette has 9 such macules. - **Axillary or inguinal freckling (Crowe sign)**: This is criterion 2 of the 2021 NIH Revised Diagnostic Criteria and is explicitly present in this patient. It typically appears at age 3–5 years and is highly specific for NF1. - **Presence of cutaneous neurofibromas or plexiform neurofibromas**: This is criterion 3 of the 2021 NIH Revised Diagnostic Criteria. The patient has four cutaneous neurofibromas, and the father has a plexiform neurofibroma, both of which satisfy this criterion. **High-Yield:** NF1 café-au-lait macules have smooth "coast of California" borders; McCune-Albright has irregular "coast of Maine" borders—this distinction is essential for differential diagnosis and genetic counseling. [cite: NF1 Revised Diagnostic Criteria 2021 (Legius et al); Nelson Pediatrics 22e — Neurocutaneous Syndromes]
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