Supplementary Material for: A Silvery Hair Revolution: Case Report of Marie Antoinette syndrome in a child

Background: Sudden diffuse hair whitening (canities subita) is exceptionally rare in childhood and may mimic congenital pigment dilution syndromes.
Case presentation: We describe a 17-month-old girl who developed abrupt hair depigmentation during hospitalization for septic shock. Clinical examination, trichoscopy, and light microscopy confirmed diffuse alopecia areata and achromotrichia. Hematologic and immunologic investigations were normal. Spontaneous repigmentation occurred within three months.
Conclusion: This case—one of the youngest reported—highlights systemic stress as a potential trigger for pediatric canities subita associated with diffuse alopecia areata and underscores the importance of distinguishing it from congenital silvery hair syndromes, which carry markedly different prognostic and therapeutic implications.