We present the case of a 27 year‐old female with a linear array of brown keratotic papules with a raised nodule within, located in the right mid upper inner thigh. A biopsy of the nodule showed a superficially invasive squamous cell carcinoma. Subsequent excision of the entire lesion showed an epidermal nevus without residual carcinoma. Squamous cell carcinomas developing within an epidermal nevus constitute an unusual association, mostly occurring in long standing lesions of elderly patients. Other epithelial neoplasms described arising within epidermal nevi include basal cell carcinomas, malignant eccrine tumors and keratoacanthomas. Although our patient did not have an identifiable epidermal nevus syndrome, the presence of a squamous cell carcinoma within an epidermal nevus in a young person suggests increased susceptibility to tumor development. Moreover, chromosomal aberrations have been described in epidermal nevi, including chromosomal breakage and variegated translocation mosaicism. We suggest that the presence of an epidermal nevus should alert the clinician for the potential development of a malignant neoplasm within it, including squamous cell carcinoma, even in the absence of an identifiable hamartoma‐neoplasm syndrome.