Dowling-Degos-Like Flexural Hyperpigmentation in a Two-Year-Old Saudi Girl.

Dowling-Degos disease (DDD) is a rare, autosomal dominant pigmentary disorder typically characterized by adult-onset reticulate hyperpigmentation in flexural areas. Early-onset cases are exceptionally rare. A two-year-old Saudi girl presented with a one-year history of progressive, asymptomatic, velvety hyperpigmented plaques involving the axillae, anogenital region, and face. Histopathological analysis showed epidermal acanthosis with elongated rete ridges and prominent basal hyperpigmentation, consistent with DDD. Immunohistochemistry (SOX10) confirmed increased melanocytes at the rete ridge tips. This report describes what is, to our knowledge, the earliest documented case of DDD-like pigmentation in a patient under three years of age. It underscores the vital role of histopathological correlation in diagnosing pediatric pigmentary disorders, especially when genetic evaluations are inconclusive, and highlights the need for further research into the genotype-phenotype variations of early-onset disease.