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Case Reports

Abstract

Inflammatory Linear Verrucous Epidermal Nevus (ILVEN) is a rare mosaic variant of epidermal nevus (EN) typically presenting in early childhood as pruritic, linear, hyperkeratotic plaques. Although secondary tumors have occasionally been reported in EN and ILVEN, adnexal tumors remain extremely rare. Syringocystadenoma papilliferum (SCAP) is a benign adnexal neoplasm that arises from apocrine or eccrine sweat glands, often developing within hamartomatous lesions such as nevus sebaceus. We report the case of a 10-year-old female with a linear lesion behind the right ear, which had been progressively enlarging and recently developed a warty surface. Histopathological examination revealed verrucous epidermal proliferation with towers of parakeratosis, consistent with ILVEN. In the dermis, a ductal proliferation composed of papillary fronds lined by a dual epithelial layer with associated stromal plasma cells was identified. A final diagnosis of ILVEN with concomitant SCAP was made. Only two cases of SCAP developing within longstanding verrucous epidermal nevi in adult patients have been reported, one of which showed malignant transformation. This is the first reported case of SCAP arising in a pediatric ILVEN patient in the literature with unknown true biological relationship. This case also highlights the importance of long-term monitoring of ILVEN lesions. Given our case demonstrates SCAP developing early within ILVEN, it suggests that recent morphological changes in ILVEN, such as verrucous proliferation, should prompt consideration for biopsy, as these lesions may carry risk of malignant transformation. These findings also present diagnostic challenges, particularly in ILVEN, where SCAP may clinically mimic or coexist with verrucous plaques.