Temporomandibular joint disorder (TMD) is an umbrella term to describe chronic and acute pain generally relating to the temporomandibular joint. This joint can often become inflamed, displaced (the interposing disk) or injured. TMD can result in extreme cases of facial pain leading to disruptions of normal, facial functioning.
Typical TMJ Problem Area. Image via http://www.teethgrindingtreatment.com/teeth-grinding-tmj/
As in life, things are not always what they seem! TMD is a fairly common, and well-understood disorder. There have been cases though where a patient presents with TMD symptoms, but instead the real culprit is a lesion compressing the associated structures thus mimicking typical TMD symptoms. Such a lesion could be a Pleomorphic adenoma.
Pleomorphic adenoma is a common variety of salivary gland tumours, though clinical diagnosis can often be difficult. Especially when the tumour presents itself deep within the gland. While these tumours are usually asymptomatic, they do occasionally present with the symptoms of TMD.
Read my case study of a 43-year old man who presented unique facial pain issues: http://www.cda-adc.ca/jcda/vol-74/issue-1/63.pdf
Now this can be a problem for both diagnosis and treatment of the tumour.
The slow-growing, and normally painless tumour can also be associated with facial palsy or chronic pain. If it were to grow large enough, it could also impede proper chewing, mandibular movement, and could cause entire muscular paralysis.
Read my full insight into Pleomorphic adenoma and its common association with TMD symptoms here: http://www.jcda.ca/article/d15/