Supplementary Material for: Oral isotretinoin for facial discoid dermatosis (FDD): effectiveness, safety, and clinical suitability. Case report of complete response and literature review

Introduction: Facial discoid dermatosis (FDD) is a rare dermatological condition, first described in 2010. Its aetiology remains unknown and it is distinguished by its resistance to several treatments, both topical and systemic. The lack of documentation in the medical literature makes this disease a significant diagnostic and therapeutic challenge. Case presentation: A 51-year-old woman consulted for the appearance of pruritic skin lesions on the face, neck and upper chest of 2 months' duration. She underwent various topical and systemic therapies without complete resolution over a period of 9 months. Histological examination revealed psoriasiform irregular epidermal hyperplasia, mild spongiosis, parakeratosis and hypogranulosis. In the superficial dermis, perivascular lymphocytic infiltrates were observed. Given the findings described and the refractoriness to multiple treatments employed, the diagnosis of FDD was established. Low-dose isotretinoin administration led to complete resolution of the skin lesions, with no associated adverse effects observed during the course of treatment. Conclusion: We present the first reported case of FDD in a middle-aged woman who was successfully treated with low-dose isotretinoin, resulting in complete resolution of the condition. This finding underlines the potential of isotretinoin as an effective and well-tolerated therapeutic option, especially in women of childbearing age. We also provide a comprehensive review of the treatments for FDD that have been documented in the literature.