Pleomorphic Dermal Sarcoma Does Not Represent an Entity Different From Atypical Fibroxanthoma

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.

[Translated article] Lymphovascular Invasion and High Mitotic Count Are Associated With Increased Risk of Recurrence in Pleomorphic Dermal Sarcoma

BACKGROUND AND OBJECTIVE

Atypical fibroxanthoma and pleomorphic dermal sarcoma (PDS) are rare mesenchymal tumors. Due to the low incidence of PDS and a historically confusing nomenclature, little is known about the true aggressiveness of this tumor. The aim of this study was to investigate clinical and histologic risk factors for recurrence in PDS.

MATERIAL AND METHODS

Retrospective, observational, bicentric study of 31 PDSs diagnosed and treated at Hospital Clínico Universitario de Valencia and Instituto Valenciano de Oncología in Valencia, Spain, between 2005 and 2020. We described the clinical and histologic features of these tumors and performed univariate analysis and multivariate Cox regression analysis.

RESULTS

In the univariate analysis, tumor recurrence (P<.001), necrosis (P=.020), lymphovascular invasion (P=.037), perineural invasion (P=.041), and mitotic count (<18 vs ≥18 mitoses per 10 high-power fields) (P=.093) were associated with worse disease-free survival. In the multivariate Cox regression analysis, mitotic count and lymphovascular invasion retained their significance as predictors of worse disease-free survival (P<.05).

CONCLUSIONS

PDS is an aggressive tumor in which a high mitotic count (≥18) and lymphovascular invasion are associated with a higher risk of recurrence and worse disease-free survival. Necrosis and perineural invasion are also probably linked to increased tumor aggressiveness.