Malignant mesenchymal tumors of oropharyngeal mucosa are rare. Those with fibroblastic and histiocytic differentiation in the skin are called atypical fibroxanthoma (AFX) and in the soft tissue undifferentiated pleomorphic sarcoma (UPS). Here we present a case of an older patient with a history of multiple basal cell carcinomas and recently with a rapidly growing polypoid lesion in the mucosa of posterior oropharyngeal wall with AFX/UPS morphology. The differential diagnosis, histological pitfalls of this poorly characterized mesenchymal lesions, and the challenges associated with treatment are discussed.