A Case Report of a Mild and Atypical Presentation of Proteus Syndrome.

Proteus syndrome (PS) is a rare genetic disorder caused by mosaic AKT1 mutations, leading to progressive and asymmetric overgrowth. We report a mildly symptomatic 12-year-old male with left lower limb overgrowth and an epidermal nevus, whose diagnosis was confirmed through molecular diagnostics. Targeted NGS identified the pathogenic AKT1 c.49G>A mutation in affected tissues, supporting the diagnosis despite the absence of hallmark features like cerebriform connective tissue nevus. This case highlights the importance of genetic testing in subtle presentations of PS, enabling early diagnosis, monitoring, and intervention to mitigate potential complications.