Head‐and‐neck dermatofibrosarcoma protuberans: Survival analysis and Clinically relevant immunohistochemical indicators.

Background: Head and neck dermatofibrosarcoma protuberans (HNDFSP) is extremely rare and not entirely understood. Objective: To investigate the clinicopathological features of HNDFSP and identify the expression of its clinically relevant indicators, with the expectation of improving the existing treatment strategies. Methods: A long‐term follow‐up of patients with HNDFSP who received treatment between 2000 and 2021 at Shanghai Ninth People's Hospital was conducted. The clinical, histological, and immunohistochemical data of the patients were retrieved and analyzed. The endpoint of the study was the incidence of significant disease‐related clinical events (recurrences or metastasis). Results: A total of 49 patients with HNDFSP were included in the study, with males (92.7%) predominating than females (7.3%). Eighteen patients developed recurrent disease (36.8%) after surgery, and the median time of recurrence was 48 months (interquartile, 20–74 months). Metastasis occurred in two cases (4.1%). Two patients died during follow‐up, both with local recurrence, and one of them with intestinal metastasis. Post‐operation radiotherapy was administered to eight patients (16.3%) and the effect in local control was remarkable. Age, tumor size, and negative margins with sufficient safety width were the main independent factors affecting the disease‐free survival. Several potential targeted therapeutic indicators, including EZH2 (80.0%), EGFR (91.4%), PDGF (97.1%), PD‐L1 (77.1%), and VEGF (77.1%), were positively expressed in most tumor samples. Conclusion: HNDFSP is rare, significantly challenging to control locally, and has a worse prognosis with current treatment strategies. Wide local excision and long‐term follow‐up are needed. Radiotherapy could improve the prognosis of patients with HNDFSP. [ABSTRACT FROM AUTHOR]