Porokeratosis is a heterogeneous group of keratinising disorders characterised by the presence of particular microscopic structural changes, namely the presence of the cornoid lamella. This structure develops as a consequence of a defective isoprenoid pathway, critical for cholesterol synthesis. Commonly recognised variants include disseminated superficial actinic porokeratosis, disseminated superficial porokeratosis, porokeratosis of Mibelli, palmoplantar porokeratosis (including porokeratosis palmaris et plantaris disseminata and punctate porokeratosis), linear porokeratosis, verrucous porokeratosis (also known as genitogluteal porokeratosis), follicular porokeratosis and porokeratoma. Apart from the clinical presentation and epidemiology of each variant listed, this review aims at providing up-to-date information on the precise genetic background, introduces imaging methods facilitating the diagnosis (conventional and ultraviolet-induced fluorescence dermatoscopy, reflectance confocal microscopy and pathology), discusses their oncogenic potential and reviews the literature data on the efficacy of the treatment used, including the drugs directly targeting the isoprenoid-mevalonate pathway.

Since its description in 1995, porokeratosis ptychotropica (PP) has remained a less-recognized variant of porokeratosis (PK). The term porokeratosis ptychotropica was coined in reference to its characteristic of affecting body folds. It mimics many other dermatological diseases and is therefore often misdiagnosed. We report a patient with multiple hyperkeratotic, warty lesions across the buttocks that mimicked cutaneous tuberculosis (CTB), but histological examination confirmed the correct diagnosis of PP.