Blaschkoid Dermatosis in Childhood: A Clinical Perspective on Linear Porokeratosis

Abstract

Linear porokeratosis is a rare genodermatosis with childhood onset characterized by keratinization disorders. We present the case of an 8-year-old female schoolgirl with scaly lesions on her left upper extremity that had lasted for 5 years. Physical examination revealed a localized dermatosis on the extensor region of the left arm characterized by multiple pink annular plaques of various sizes with raised, keratotic borders and an atrophic, depressed center that converged in a linear distribution and extended to the back of the ipsilateral hand. A skin biopsy revealed thin columns of parakeratotic cells forming the cornoid lamella with underlying hypogranulosis. A diagnosis of linear porokeratosis was made and topical treatment with tretinoin 0.025% OD and simvastatin 2% OD was initiated, with clinical improvement after 4 weeks. Linear porokeratosis usually manifests in childhood due to postzygotic genetic mosaicism, which explains its distribution along Blaschko lines. This form presents the highest risk of malignant transformation, with rates as high as 19%, with squamous cell carcinoma predominating. Treatment is complex, with a low complete response rate (16%). In this context, topical statins have emerged as a promising therapeutic alternative. Conclusion: Linear porokeratosis should be suspected in Blaschkoid lesions of childhood onset. Furthermore, it requires follow-up due to its risk of malignant transformation (19%). Regarding treatment, topical statins emerge as a safe and effective alternative, although further studies are needed to validate their long-term use. patients. These predictors, however, need further work to validate reliability.