Atypical fibroxanthoma and pleomorphic dermal sarcoma: Local recurrence and metastasis in a nationwide population-based cohort of 1118 patients.

Background: The prognosis of patients with atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) remains uncertain and no standardized follow-up programs have been established.

Objective: To recommend a standardized follow-up program of patients with AFX and PDS based on nationwide long-term estimates of local recurrence and metastasis.

Methods: All patients with AFX and PDS in Denmark between 2002 and 2022 were included. Danish National Registries were used to estimate the risks of local recurrence and metastasis for AFX and PDS.

Results: The 5-year risk of local recurrence was 10% for AFX and 17% for PDS. The 5-year risk of metastasis was 0.8% for AFX and 16% for PDS. PDS metastasized within 3 years in >90% of the patients with the lungs as the primary metastasis site (50%). Invasion beyond the subcutis, perineural/intravascular infiltration, and increasing age significantly increased the risk of PDS relapse.

Limitations: Risk of misclassification and lack of detailed surgical information.

Conclusion: The follow-up of patients with AFX can be limited to clinical visits for 4 years. Patients with PDS should be followed with clinical visits and PET/CT twice a year for the first 3 years and once a year for a minimum of 1 year.