Supplementary Material for: Squamous Cell Carcinoma of the External Auditory Canal in a Patient with Netherton Syndrome

Netherton syndrome is a rare autosomal recessive disorder characterized by congenital ichthyosis, hair shaft abnormalities, atopic diathesis, and a broad spectrum of immunologic dysfunction. Although cutaneous malignancies are uncommon, affected individuals may develop early-onset tumors that can pose diagnostic and therapeutic challenges. We report the case of a 33-year-old woman with Netherton syndrome who presented with persistent left otorrhea and a granulomatous mass in the external auditory canal. Imaging demonstrated a soft-tissue lesion with focal bony erosion and suspected dural involvement, accompanied by fluorodeoxyglucose uptake in a cervical lymph node. Biopsy confirmed squamous cell carcinoma, staged as T4N1M0. The patient underwent superselective intra-arterial cisplatin infusion combined with radiotherapy, resulting in complete remission of both the primary lesion and nodal metastasis, with no evidence of recurrence over four years. Including this case, nine patients with Netherton syndrome and cutaneous malignancies have been reported, with tumors frequently arising at a young age and showing variable HPV status. Interpretation of SCC antigen may be complicated by elevations associated with atopic dermatitis. This case highlights the elevated risk of cutaneous malignancies in Netherton syndrome and underscores the need for long-term surveillance and multidisciplinary care.