Lymphovascular Invasion and High Mitotic Count Are Associated With Increased Risk of Recurrence in Pleomorphic Dermal Sarcoma. / La presencia de infiltración linfovascular y de un alto número de mitosis se asocia a un mayor riesgo de recidiva en sarcoma pleomórfico dérmico.

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.