Preoperative 3D Reconstruction Model in Slow Mohs Surgery for Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is a type of skin cancer that is extremely rare. Its standard treatment is either surgical wide-local excision (WLE) or Mohs micrographic surgery (MMS). Which method has the lowest recurrence rate is unknown. Dermatofibrosarcoma protuberans is an uncommon soft tissue sarcoma with a high propensity for recurrence. It has always remained a clinical challenge. More technology is needed to treat the disease. We reviewed our cases and published experience and evaluated whether 3D modeling could precisely define tumor morphological characteristics and assist excision in slow Mohs surgery. There were 18 dermatofibrosarcoma protuberan cases enrolled. They were treated in Shanghai Ninth People's Hospital from 2014 to 2019. All the 18 included patients presented with primary disease and no metastasis. All subjects had undergone thorough imaging examinations including CT and MRI. The 3D tumor reconstruction models were created for their tumors. We precisely estimated tumor boundaries and sizes according to those 3D models. Afterward, patients underwent slow Mohs surgery and surgical repair of tissue defects following tumor resection. The 3D tumor reconstruction models were successfully established. The predicted tumor volumes were measured in all 18 cases. The average volume was 38.5 cm³ (range: 8.4 cm³-183.6 cm³), which allowed for accurately locating the tumor. Tumors were completely removed in one stage of slow MMS surgery. In the second-stage surgery, the defects were repaired by different surgical methods including direct soft tissue closure, skin grafting, local flaps, or free flaps. Most patients experienced no significant complications. This practice indicated that the combination of a 3D reconstruction model and slow Mohs surgery achieves more precise and complete DFSP resection to decrease the recurrence rate.