Granulomatous slack skin disease: a new combined proton and photon therapy approach with a reported case response

Purpose: Here, we report the feasibility and long-term efficacy of a granulomatous slack skin disease (GSSD) treatment with combined high-energy photon and proton beams. Patient and methods: A GSSD patient with abdominal disease volume 25 x 15 x 2-4 cm deep was recommended for treatment at this institution. In addition to photons and electrons, high-energy protons delivered with advanced planning techniques and patient positioning were used. The patient was irradiated to a total dose of 40 Gy by using 20 Gy matched photon and electrons followed by 20 Gy equivalent protons delivered by using innovative range compensation and patient positioning. Results: The test patient tolerated the treatment well and is now a 10-year survivor of the disease. Conclusions: Treatment of GSSD with protons is feasible. The range and narrow penumbra properties of the proton beam provided an ideal capability to match fields accurately to cover large volumes while also sparing underlying normal tissues.