The first step to approaching a patient with oral and maxillofacial pathology is to take a thorough history and perform a physical examination. Information gleaned from the history and physical examination will provide clues to the correct diagnosis and guide the clinician in selecting the appropriate tools to validate the diagnosis.
Obtaining the History
In taking the history of present illness, one should first establish a timeline for the disease. One should ask when the patient first noticed symptoms. Symptoms of interest include pain, paresthesia, dysphagia, dyspnea, otalgia, trismus, voice changes, weight loss, fevers, chills, and malaise. Although not necessarily present, pain is the most common presenting symptom for head and neck cancer. Paresthesia in the head and neck area is also highly concerning, and should be considered a sign of potential malignancy until proven otherwise. Either of these symptoms, when occurring without a likely explanation, should prompt a thorough investigation including a neurologic exam, imaging studies, and, potentially, tissue sampling.
The surgeon should inquire about any prior treatment or diagnostic tests. If biopsies have been performed in the past, it is essential to review both the pathology report and the pathology slides with a pathologist experienced in the diagnosis of oral pathology lesions. One should not take a prior pathologic diagnosis at face value, as errors can occur.
Other diseases, such as infectious diseases and autoimmune diseases, may present with oral lesions similar to oral cancer. Ask about symptoms that can rule in or out these other diseases if the initial history is suggestive of pathology other than cancer. The patient’s history should be reviewed for exposures, constitutional symptoms, or systemic manifestations. An acute onset, presence of fever or chills, rapid swelling, and signs of acute inflammation are suggestive of an infectious process. A chronic process with dermatologic findings, arthralgias, or multiple organ system involvement is suspicious for an autoimmune disorder.
The clinician should take the time to take a thorough past medical history. The history may provide additional information helpful for stratifying a patient’s risk for developing oral cancer. The past medical history may provide the etiology of the disease. Inquire about a history of dysplasia, immunocompromised states, other types of cancer, and a history of head and neck radiation.
A history of tobacco and alcohol use should be determined. Ask about cigarette usage in addition to other forms of tobacco use, such as snuff, cigar, or pipe tobacco. The quantity of tobacco and length of time used should be recorded. An accurate alcohol history is often difficult to gather, as most people underestimate their use. It is helpful to corroborate history with family and friends. It is also helpful to inquire about betel nut use, particularly in patients of Asian or South Asian descent. One should inquire about environmental exposures at work and home. A history of dental neglect should be recorded.
The Focused Physical Examination
The focused examination of the oral and maxillofacial pathology patient should always include an examination of the neck, the face, the salivary glands, and the oral cavity. Examination of the eyes, ear, nose, pharynx, larynx, and cranial nerves should be performed as directed by the patient’s presenting symptoms and the clinician’s differential diagnosis.
Once the initial history and physical exam are completed, the next step in the clinical evaluation is often the ordering of imaging studies. There are a number of modalities available to the oral and maxillofacial surgeon, each with their own strengths, limitations, and varying degrees of invasiveness. As with any study, it is important for the surgeon requesting the imaging to have specific questions to be answered. When requesting imaging, the surgeon aims to: (1) better characterize the location, composition, and behavior of the lesion to assist in a diagnosis; (2) delineate the full extent of the lesion and its proximity to adjacent vital structures to aid in prognosticating as well as treatment planning; and (3) in the case of malignant disease, determine whether there is metastatic spread to the neck lymphatics.
Plain radiographs are two-dimensional images created by projecting X-rays through a patient on to a film or digital sensor. These include, dental panoramic tomograms, dental radiographs and chest radiographs.
A chest radiograph to screen for metastasis or synchronous lung primaries is part of the standard comprehensive evaluation of a patient diagnosed with head and neck cancer. Many of the risk factors that predispose a patient to developing oral cancer are also risk factors for other pathology. As many as 10% of oral cancer patients have chest metastases and 5% of patients have synchronous lung carcinomas that are detected on chest imaging.
Dental radiographs, such as periapical, bitewing, and occlusal films, are sometimes helpful in the evaluation of lesions of the dentate segments of the mandible and maxilla.
The dental panoramic tomogram (orthopantomogram or Panorex) is a film that is commonly used by dentists and oral and maxillofacial surgeons. Much like other dental radiographs, it is quick and inexpensive. It also has the advantage of being able to effectively image the maxilla and mandible. For these reasons, it is routinely part of the initial assessment of a patient presenting with pathology of the oral and maxillofacial region, and can be very helpful in diagnosing tumors and cysts of the jaws.
Computed Tomography (CT)
CT allows the surgeon to appreciate a tumor’s location and size in three dimensions, thus accurately defining a tumor’s relationship to important vital structures, such as the great vessels, skull base, and orbit. In addition, CT is far superior in appreciating differences in soft tissue planes and vasculature. Fat, muscle, and water can be differentiated fairly easily. This ability is further enhanced by contrast. This has also allowed surgeons to screen for nodal metastasis with reasonable sensitivity.
Although the cost of a CT scan is decreasing as accessibility increases, the study still remains expensive. The effective dose of radiation from a head and neck CT is relatively small when compared to annual exposure to natural radiation. But, at around 1000–4000 μSv, it is not insignificant. This is, however, still a greater effective dose than that of plain radiography, and may be of concern to some patients, especially when serial CT scans are required, or the patients are children. Another drawback of the use of CT in the maxillofacial region is the obscuring of the image from artifacts arising from high-density materials such as dental filling or surgical hardware.
Recently, the cone-beam CT is an iteration of the technology that has been increasingly adopted for use in the oral and maxillofacial region, in particular for use in prosthodontic and orthodontic treatment planning, but also for use in diagnosing pathology as well as surgical and radiotherapy treatment planning. Cone-beam CT uses an X-ray beam in the shape of a cone that rotates and scans the entire volume of interest, as opposed to a conventional fan-beam CT, which uses a fan-shaped X-ray that rotates around and advances along the volume of interest. Because of this, cone-beam CT decreases the effective dose to roughly around 23–52 μSv. In addition, cone-beam CT is less susceptible to dental artifacts. The spatial accuracy is comparable to conventional CT, with its relative geometric error measured in tenths of a millimeter. However, some of the drawbacks of the cone-beam CT are its inferior soft tissue visualization, which limits its use in diagnostics for oral and maxillofacial pathology and staging of the neck, and that it is limited in the total volume that can be visualized with a single scan.
Another advance in surgical planning has been the use of conventional CT to create stereolithic models and customized surgical reconstruction plates.
Magnetic Resonance Imaging
MRI is a technology that is based upon the science of nuclear magnetic resonance. The system works by placing a patient in a magnetic field that aligns the protons of hydrogen atoms (most commonly found in water) in the direction of the field. A second magnetic field is then momentarily introduced that causes protons to be deflected from this axis and, in the process, absorb some of its energy. Once this second field is released, the protons that were previously deflected return to the initial axis of the first magnetic field and release the absorbed energy as a radiofrequency. The radiofrequencies are then detected by the MRI scanner and are used to determine the position of the respective protons. Several of these additional fields are used along the volume of interest and the information is compiled into a three-dimensional image that can be viewed in sections. Gadolinium, a paramagnetic material, is used to enhance areas of inflammation or increased vascularity.
As with CT, the MRI creates spatial imaging that allows the surgeon to visualize a tumor in three dimensions and appreciate the tumor’s relationship to adjacent structures. In addition, MRI has several advantages over CT. It has superior soft tissue resolution, and, as such, is the preferred imaging of choice of neurologic pathology. It is minimally affected by artifacts from high-density materials. MRI also does not use ionizing radiation and is considered non-invasive. In addition, the use of certain protocols, namely magnetic resonance angiography (MRA), allows for the imaging and detection of blood flow, which is useful in the preoperative assessment of vessels for microvascular reconstruction.
As the technology uses a strong magnetic field, implanted paramagnetic materials, such as pacemakers, cochlear implants, deep brain stimulators, or older vascular aneurysm clips, are an absolute contraindication for MRI. These can cause motion and thermal injury to surrounding tissues. MRI scanners are much slower than CT scanners, with scanning times up to 40 minutes on older machines. Because of this, motion artifacts are a problem and patients who are unable to lie still (such as children) may require anesthesia to have an MRI. Furthermore, patients who suffer from claustrophobia may also find undergoing an MRI difficult.
Positron Emission Tomography (PET) and PET/CT
PET is an imaging modality that highlights areas of the body with increased metabolic activity. Radionuclides are bound to molecules that are important to human metabolism. The most common tracer used in PET is F2-fluoro-2deoxy-D-glucose (FDG), which is a radioactively labeled glucose. FDG is administered intravenously and becomes sequestered in cells that are actively taking up glucose. Malignant cells that are more mitotically and metabolically active would then have relatively greater uptake than surrounding nonmalignant cells. Once sequestered in cells, the FDG undergoes radioactive decay to a more stable molecule, emitting positrons in the process. These positrons combine with electrons within the adjacent tissues and annihilate, resulting in a release of gamma rays 180° from each other. These gamma rays are then picked up by detectors within the PET scanner. PET is often combined with CT, or even MRI, to give enhanced localization.
Ultrasound images are created from the recording of the amplitudes of reflected high-frequency sound waves. The primary advantage of this tool is that anatomy can be visualized dynamically in real time by the sonographer. Other advantages are that ultrasound is extremely safe and relatively inexpensive.
Ultrasound has several indications. It is useful in evaluating superficial nodules of the neck, salivary glands, and thyroid gland. Ultrasound is very effective in identifying cystic lesions, which appear as well defined hypoechoic (dark) masses. Benign tumors of the salivary and thyroid glands are similarly well defined, lobular, and hypoechoic. Lesions that are less well defined are suspicious for malignancy and should prompt the clinician to order additional studies.
Obtaining a Tissue Diagnosis
Much information can be gathered from taking the history, performing the physical exam, and acquiring the appropriate imaging studies. However, histologic analysis is absolutely essential for a definitive diagnosi/>