Methylaminolaevulinate-based photodynamic therapy of Bowen’s disease and squamous cell carcinoma

MAL-PDT may represent a valuable, effective and well tolerated treatment option with good cosmetic outcome for superficial, well-differentiated (Broders' scores I and II) BD and microinvasive SCC. In contrast, its use for superficial SCCs with a microinvasive histological pattern and for nodular, invasive lesions, particularly if poorly differentiated keratinocytes are present (Broders' scores III and IV), should be avoided.