Development of Segmental Superficial Actinic Porokeratosis during Immunosuppressive Therapy for Pemphigus Vulgaris

Abstract

Porokeratosis (PK) is a heterogeneous group of heredi-tary or acquired disorders of keratinization with a broad clinical spectrum and various aetiologies. Common to all PK is the typical histological feature of a cornoid lamella, which corresponds to the hyperkeratotic rim of slowly centrifugal spreading lesions (1). Several subtypes of PK have been distinguished based on size, localization and number of lesions. However, porokeratosis of Mibelli (PKM) and disseminated superficial actinic porokeratosis (DSAP) are the most common clinically encountered subtypes.CASe rePorTA 68-year-old woman with pemphigus vulgaris since 2007 had received systemic glucocorticosteroids to-gether with azathioprine and mycophenolate mofetil, without sufficient control of the autoimmune disorder. A cyclophosphamide/dexamethasone pulse therapy at 4-week-intervals was initiated instead. Unexpectedly, within 9 months after initiation of the pulse therapy the patient developed multiple asymptomatic erythematous plaques 3–8 mm in size on the right leg (Fig. 1a). The lesions were characterized by slightly elevated margins with either atrophic centres or overlying hyperkeratosis (Fig. 1b). Histopathological examination showed a cor-noid lamella with underlying vacuolated keratinocytes and absent granular layer indicative of porokeratosis (Fig. 2). Typical predilection sites for DSAP, such as lower legs and forearms, were not involved. There was no family history of DSAP.DISCUSSIoNDSAP is an autosomal dominant disorder clinically characterized by symmetrical development of disse-minated keratotic lesions predominantly on the lower extremities of middle-aged individuals. Ultraviolet (UV)-light exposure has been proposed as one of the triggering factors (1). The presented case is unique because of the segmental development of DSAP in close temporal association to increase of immunosuppressive therapy. Immunosup-pression has previously been considered as a triggering factor for the development of porokeratosis (2). occur-rence of porokeratosis has been described in transplant patients and in patients with primary or secondary im-