Porokeratosis (PK) is a clonal epidermal disorder of keratinization characterized by annular lesions with an atrophic center and a hyperkeratotic edge. Six clinical variants are recognized. Among them, disseminated superficial actinic porokeratosis (DSAP) is characterized by the presence of multiple ring-shaped, keratotic and anhidrotic lesions of 0.5-1 cm in size, symmetrically distributed in light-exposed areas. A relationship between these lesions and malignancy was established by Taylor, who found a chromosomal instability in fibroblast cultures from PK lesions. The incidence of malignant degeneration in PK is approximately 7%, with large lesions, longstanding duration, the linear type and previous ionizing radiation being the greatest risk factors. We herein report a case of multiple skin tumors arising from a lesion of DSAP. A 78-year-old female presented with multiple brownish to black colored annular patches which began about 20 years previously and multiple black colored hyperkeratotic papules which began about 2 years ago. The histopathological findings of several biopsies had the characteristics of squamous cell carcinoma, squamous cell papilloma, keratoacanthoma including DSAP. We thought the long duration and large size of the DSAP lesions could be the risk factor of malignant degeneration.