Photodynamic therapy as adjuvant treatment of extensive basal cell carcinoma treated with Mohs micrographic surgery.

MOHS MICROGRAPHIC surgery has proven to be an effective treatment for many skin cancers and especially nonmelanoma skin cancers. Because of the 100% margin control during the operation, maximum conservation of healthy tissue and high cure rates are obtained. This makes Mohs micrographic surgery a very suitable treatment modality for aggressive, large and recurrent basal cell carcinomas especially in the face. Photodynamic therapy is a treatment modality still under investigation. Nevertheless, it is increasingly being used in the treatment of superficial basal cell carcinomas and Bowen’s disease and premalignant skin disorders, such as actinic keratosis. In dermatology, often aminolevulinic acid is used in topical application. Aminolevulinic acid is a precursor in the heme biosynthesis pathway and is converted into the photosensitizer protoporphyrin IX. After several hours, a sufficient amount of protoporphyrin IX is synthesized for an effective response to photodynamic therapy. Generally, single illuminations with total light dose between 50 and 150 J/cm and fluence rates between 50 and 100 mW/cm are used with wavelengths around 635 nm Good results have been reported after treatment of superficial basal cell carcinomas, with complete response rates of 90% to 100%. For nodular basal cell carcinomas, however, complete response rates of only 10% to 71% are obtained with photodynamic therapy. A wide variety of basal cell carcinoma histopathologic subtypes have been described. Classified by growth pattern, basal cell carcinomas can be subdivided into aggressive (morphea, micronodular, infiltrative type) and nonaggressive (nodular, superficial type) tumors. Small buds off basaloid tumor cells that arise from and are in continuity with the epidermis and extend into the superficial dermis histologically characterize superficial basal cell carcinoma. Previously, this tumor type was inappropriately being described in literature as multifocal or multicentric superficial basal cell carcinoma. In threedimensional reconstruction, the tumor buds have been shown to form anastomosing or interconnecting complexes. Before surgery is performed, a biopsy is taken to determine the histopathologic subtype. Nevertheless, it is well understandable that a biopsy only gives an impression of a small part of the entire tumor, which often, in more than 35% of cases, consists of mixed subtypes. In accordance, we noticed that, especially in patients with multiple skin cancers in the face, a solid or aggressive type basal cell carcinoma can be superficial at the borders. These fields of superficial growing basal cell carcinoma can cause large defects when treated by surgical excision. We report four cases of facial basal cell carcinoma treated with Mohs micrographic surgery, where we used photodynamic therapy as an adjuvant therapy for the remaining superficial tumor parts. During the Mohs procedure, situations presented themselves that gave rise to reconsideration of continuation of our started treatment. We treated the surroundings of the surgical defect with photodynamic therapy by using a light source of 600 to 730 nm (Waldmann PDT 1200 unit), with fluence rates ranging from 90 to 100 mW/cm and light doses from 60 to 100 J/cm, after 4-h application of freshly prepared 20% aminolevulinic acid oil in water. The area treated was delineated with 2 to 5 cm surrounding the wound or scar. This was not a fixed area in all patients. Where possible, for instance, on a forehead, a margin of 5 cm was used; where this was