Patients referred from an otorhinolaryngologist with a chief complaint of earache or other ear symptoms are common in a temporomandibular disorders (TMD) clinic. These patients often complain of other symptoms, such as headache, facial pain, and limited mouth opening, all of which can be present in a patient suffering from a nasopharyngeal carcinoma (NPC). The aim of this case report was to describe the signs and symptoms of NPC and discuss possible causes for the misdiagnosis of NPC as TMD. The characteristics of 8 NPC patients reported in the literature whose cancer was initially misdiagnosed as TMD and those of an NPC patient with TMD-like symptoms treated at the clinic of 1 of the authors are described, and the reasons for misdiagnosis are discussed. A revision of Trotter's syndrome for the differential diagnosis of TMD is proposed. There is a need for detailed exclusion criteria to be applied prior to the assignment of a clinical diagnosis based on the Research Diagnostic Criteria for TMD.