Treating oncologic patients remains a challenge for surgeons aiming to provide patients with safe margins of resection while maintaining the highest possible quality of life. The latter, in the case of malignancies, requires using sophisticated methods of reconstruction. Thus, we present a case of a 75-year-old patient treated in our department with a rare neoplasm in the region of the temporomandibular joint—a myxofibrosarcoma that was mimicking an inflammatory lesion. The patient underwent two surgeries—firstly alloplasty of the TMJ due to the suspicion of an inflammatory lesion, lately extended to the resection of glenoid fossa and subtemporal fossa contents when the mandible was reconstructed using UHMW-PE (ultra-high molecular weight polyethylene). The patient was also referred for adjuvant radiotherapy and has remained disease-free for over 96 months with very good aesthetics and function of the mandible. The presented case highlights not only the need for increased oncologic awareness but also the possible use of UHMW-PE as a reconstruction material in the broad resection of the maxillofacial region.