The medical records of 3 patients who visited our hospital with preauricular pain and limited jaw movement were retrospectively reviewed. All were clinically evaluated, diagnosed through the use of conventional radiographs, and initially treated as having temporomandibular disorders (TMD). However, their symptoms did not improve and even increased or facial swelling occurred, so advanced imaging modalities were used to make a differential diagnosis. The final diagnoses of the patients were cellulitis, an inflammatory pseudotumor, and pigmented villonodular synovitis. In addition to these 3 patients, 50 others who were initially misdiagnosed during a clinical examination as having TMD on conventional radiographs were reviewed in the English-language literature. When diagnosing patients with TMD symptoms, we must consider the possibility of unusual causes, including tumors and infections or inflammations. Furthermore, in addition to usual TMD treatment procedures, an advanced radiologic examination should be performed to aid in the differential diagnosis of all patients with unceasing pain and mouth-opening limitation.