In situ photoimmunotherapy is ineffective in treating deeply invasive squamous cell carcinoma

In situ photoimmunotherapy (ISPI) can be a treatment option for selected cutaneous malignancies in patients who are not surgical candidates. We herein report the case of a large, ulcerating poorly differentiated squamous cell carcinoma (SCC) affecting the foot of an elderly woman with chronic arsenicosis. The tumor failed radiotherapy, intralesional methotrexate, and 5-aminolevulinic acid photodynamic therapy (PDT). Because the patient was reluctant to undergo amputation, the recurrent tumor was treated with ISPI using topical imiquimod application followed by PDT. Despite some initial improvement in the superficial part of the tumor, tumor invasion to the underlying bone was detected. This case illustrates the lack of efficacy of ISIP in treating a high-risk invasive SCC