Bullous Congenital Ichthyosiform Erythroderma with Tinea Capitis in Half-Siblings: Rare Phenomenon in Ichthyosis with Co-Existing Trichophyton rubrum Infection and Blocker Displacement Amplification for Mosaic Mutation Detection

<b>Background/Objectives</b>: Bullous congenital ichthyosiform erythroderma (BCIE) is an inherited keratinization disorder caused by pathogenic variants in specific genes. Here, we report a pair of half-siblings with BCIE and tinea capitis due to <i>Trichophyton rubrum</i> (<i>T. rubrum</i>) and then review the species of ichthyosis previously reported with <i>T. rubrum</i> infection. <b>Methods</b>: We performed dermatological examination, fungal culture, and genetic analysis using whole-exome sequencing (WES) and blocker displacement amplification (BDA)-based Sanger sequencing. Both patients received oral terbinafine once daily and topical bifonazole gel for tinea capitis. <b>Results</b>: The pair of half-siblings had exhibited generalized scaling and hyperkeratosis since birth. Both siblings subsequently developed scalp pustules and hair loss for several months. Genetic analysis identified a pathogenic variant in the keratin 10 (<i>KRT10</i>) gene, confirming BCIE diagnosis. Additionally, fungal culture revealed <i>T. rubrum</i> infection. The patients responded positively to oral terbinafine antifungal treatment. <b>Conclusions</b>: This case highlights the potential susceptibility of patients with BCIE to fungal infections, warranting clinical vigilance. Furthermore, it demonstrates the utility of the BDA-based mutation detection method for diagnosing BCIE, suggesting its promise for advancing personalized diagnosis and management in hereditary skin diseases.