A popping or clicking jaw is a classic sign of the common TMJ disorder, but cancer can also affect the jaw and cause popping, mimicking a benign TMJ problem.
Since cancer can grow just about anywhere in the body, why would the jaw bone or temporomandibular joint be exempt from this rule?
A variety of conditions can mimic TMJ disorder (aka TMD), and cancer – one of the greatest masqueraders – is one of them.
A disease process that affects the jaw can make it produce popping or clicking sounds, plus cause other symptoms such as soreness, stiffness, pain chewing and facial swelling.
When cancer is the cause of TMJ disorder, the treatment that’s typically applied by a dentist will not work.
Further investigation into such a patient’s worsening symptoms leads to an imaging study that shows a cancerous mass.
“Patients and practitioners often embrace the diagnosis of a temporomandibular disorder (TMD) for patients presenting with unexplained orofacial pain or dysfunction, without adequate consideration of other possible diagnoses,” says a paper in Journal of Orofacial Pain (Fall, 1999).
Certainly, when a patient presents to a dentist with complaints of jaw popping and other symptoms associated with TMD, the dentist’s first thought isn’t going to be, “This could be cancer that has spread from a prostate tumor.”
Cancer in the jaw isn’t necessarily a primary tumor; it could be a metastasis from a distant site in the body.
A paper in Oral Surgery, Oral Medicine, Oral Pathology Oral Radiology (Nov. 1985) describes a case of prostate cancer that had metastasized to the mandibular condyle (jaw joint).
Here is the paper’s summary of how cancer can mimic benign TMJ disease:
“A metastatic tumor involving the mandibular condyle presented symptoms of temporomandibular joint (TMJ) dysfunction.
“A review of the literature revealed fifteen additional cases of metastatic lesions of the mandibular condyle, seven which also demonstrated TMJ-related symptoms as the initial manifestation of malignant disease.
“Symptoms of TMJ dysfunction coupled with radiographic evidence of a destructive lesion or pathologic fracture should suggest a possible malignant process indicating the need for biopsy.”
The Journal of the American Dental Association (Feb. 1990) reports, “When a patient is initially diagnosed with TMJ disease, failure to respond to appropriate therapy should alert the clinician that the initial diagnosis may be incorrect.”
This paper cites the case of a patient with malignant Schwannoma (not the vestibular type, which is benign) who had originally been misdiagnosed with TMJ disorder.
The existence of cancer mimicking a benign problem with the jaw does not mean that jaw cancer is common.
The JADA even states, “This is only the second reported case of this tumor [Schwannoma] with TMJ symptoms.”
Another paper, called “Metastatic Carcinoma of the Mandibular Condyle Presenting As Temporomandibular Joint Syndrome” states:
“It has been estimated that fewer than one percent of all tumors metastasize to the maxillofacial area.”
The paper, appearing in The Journal of Oral and Maxillofacial Surgery (Rubin et al) points out, however, that this percentage could be an underestimation due to the following factors:
• Exclusion of the mandible in postmortem examinations
• Difficulty with radiographic interpretation of metastatic cancer to the mandible
The JOMS report cites another study (Batsakis et al) that lists the following primary cancer sites of spread to the jaw (descending order): breast, kidney, lung, colon/rectum, prostate, thyroid, stomach, skin and testes.
Though information about this is in the medical literature, the mere presence of this information does not correlate to frequency in the population of jaw cancer.
Plus, the fact that many different cancers can spread to the jaw area does not mean that jaw cancer is a common cause of popping, clicking or other symptoms of benign TMD.
The JOMS states, “Only 13 cases of metastasis to the mandibular condyle have been reported in the literature.”
However, this paper was published in 1989, and metastases can still occur to other portions of the mandible. I
n fact, most cancer mets to the mandible are in the molar and premolar regions.
These areas, when affected by cancer, can mimic TMD symptoms such as popping, clicking or issues with chewing.
Jaw cancer can also be from direct extensions of local malignancy from the skin, parotid, ear or nasopharynx.
Benign tumors can also arise in the mandibular condyle.
With all of that said, there is no answer to the following question: What percentage of patients, presenting with a popping jaw and other classic TMD symptoms, have jaw cancer (either local or distant metastatic)?
What IS clear, though, is that cancer – as a cause of jaw popping – is exceedingly rare.
At the same time, dentists need to be vigilant about ruling this out before proceeding with treatment designed for benign TMJ disorder.
“Clinicians should include the suspicion of cancer in the differential diagnosis, in particular when patients have a previous history of malignant neoplasm or do not respond to treatment appropriately,” says a paper in Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology (August 2010).