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Case ReportsAbstract
Proteus syndrome is an ultra-rare mosaic disorder caused by somatic activating mutations in the AKT1 gene, characterized by asymmetric, progressive, and disfiguring overgrowth of multiple tissues. We report the case of a 58-year-old woman with a congenital right clubfoot and chronic verrucous lesions on the right foot, previously misdiagnosed and treated as recalcitrant viral warts for over a decade. On examination, severe structural deformity, cerebriform hyperkeratotic plaques, infrapatellar lymphedema, and a chronic plantar ulcer were noted. Based on clinical suspicion, differential diagnoses included verrucous carcinoma, chromoblastomycosis, and Proteus syndrome. Initial biopsy reported atypical squamous proliferation with features suggestive of verrucous carcinoma and associated stasis dermatitis. However, expert dermatopathologic review revealed pseudoepitheliomatous hyperplasia with dense dermal collagenous proliferation and cerebriform fibroblastic changes, establishing the diagnosis of Proteus syndrome. Imaging confirmed soft tissue overgrowth, neovascularization, chronic arthropathy, and peripheral arteriopathy. Given the functional compromise and ulceration, elective amputation was discussed as a multidisciplinary decision. This case is remarkable due to its late diagnosis, isolated limb involvement, and initial misinterpretation as a malignancy. Cerebriform fibroblastic proliferation—an underrecognized but pathognomonic feature—proved pivotal for diagnosis in the absence of genetic testing. The case highlights the importance of including rare mosaic disorders in the differential of chronic verrucous lesions and underscores the diagnostic value of specialized histopathologic evaluation. Greater clinical awareness and early recognition of Proteus syndrome could prevent prolonged diagnostic delays, mismanagement, and unnecessary patient morbidity. Histology served as the cornerstone for accurate clinical recognition.