Polymorphous Adenocarcinoma, Low Grade Variant, Colliding with a Neurofibroma.

Collision tumors, composed of two distinct benign or malignant neoplasms, are rarely reported in the oral cavity. We present a case of a 61-year-old female with an asymptomatic non-demarcated lump on the soft palate of unknown duration. An incisional biopsy revealed the presence of two neoplastic populations, a neurofibroma that was partially infiltrated by a polymorphous adenocarcinoma, low-grade variant. Total surgical excision was performed, with uneventful follow-up period. The development of collision tumors may be incidental, although molecular events may influence the pathogenetic mechanism of the phenomenon.