Dermoscopy for the Diagnosis of Porokeratosis

Dermoscopy is a non-invasive diagnostic technique, which is performed by means of different incident light magnification systems using an oil immersion technique. It allows to observe pigmented and vascular structures, from the stratum corneum to the papillary dermis. Dermoscopy is therefore particularly useful in those skin disorders in which the stratum corneum, epidermis and papillary dermis are involved. It is mostly used for the diagnosis of pigmented skin tumours, but its usefulness has also been reported for the in vivo detection of Sarcoptes scabiei. Additionally, this technique may be used for the diagnosis of verrucae vulgaris, psoriasis and other diseases with epidermal involvement. Porokeratoses are a group of disorders of keratinization characterized by annular lesions surrounded by a characteristic keratotic border which corresponds to a typical histopathologic feature, namely, the cornoid lamella. The cornoid lamella is a column of parakeratotic cells placed on a depression of the epidermis where the granular layer is absent. Though nonpathognomonic, the cornoid lamella is the most distinctive feature of the various types of porokeratosis. These varieties include the plaque type originally described by Mibelli (few lesions located on the extremities with a cornoid lamella which could be thick up to 10 mm); the superficial disseminated and superficial actinic forms, the punctate variant of palms and soles and the linear type all sharing similar histopathologic features. We report a case of disseminated superficial porokeratosis and describe the morphologic features that can be evidenced by epiluminescence microscopy examination