Squamous Cell Carcinoma Developing within Lesions of Disseminated Superficial Actinic Porokeratosis

Abstract

Disseminated superficial actinic porokeratosis (DSAP) consists of multiple annular, hyperkeratotic lesions that have a bilateral distribution on sun-exposed areas, particularly the extremities. DSAPs have a wider distribution than porokeratosis of Mibelli and usually develop during the 3rd or 4th decade of life. Squamous cell carcinoma that arises in the classical type of porokeratosis of Mibelli is well-documented, but there are only a few reports of squamous cell carcinoma in DSAP. Here, we describe a 62-year-old man with DSAP who developed squamous cell carcinoma on his right forearm.

Keywords: Disseminated superficial actinic porokeratosis; Squamous cell carcinoma.

Fig. 1

An irregular, marginated, erythematous plaque and multiple, brown, atrophic macules surrounded by well-demarcated, raised ridges on the right forearm.

Fig. 2

Biopsy specimen obtained from the erythematous plaque on the right arm. In epidermis, acanthosis and dysregulated keratinocytes with hyperchromatic, atypical nuclei are observed. A cornoid lamella composed of a column of parakeratosis is seen in the lesion of the squamous cell carcinoma (H&E, ×100).

Fig. 3

Overexpression of p53 in the epidermis of a disseminated superficial actinic porokeratosis lesion. A column of parakeratosis with underlying hypogranulosis is observed. Perivascular lymphocytic infiltrations are localized beneath the cornoid lamella (p53 immunohistochemical stain, ×200).