Faculty Bibliography

Carcinoma ex pleomorphic adenoma is a rare malignancy of the head and neck, particularly in the minor salivary glands. Most cases arise in the major salivary glands, most commonly in the parotid gland, followed by the submandibular gland. The malignant component of the tumor varies, but can be salivary duct carcinoma, adenoid cystic carcinoma, mucoepidermoid carcinoma, squamous cell carcinoma, or adenocarcinoma, not otherwise specified. Primary salivary duct carcinoma is also a rare malignancy of the head and neck. Similar to carcinoma ex pleomorphic adenoma, it is more common in the major salivary glands, with the parotid gland accounting for 88% and the submandibular gland for 10% of cases. To date, only 25 known cases of primary salivary duct carcinoma arising in the minor salivary glands have been documented, with most arising in the palate. Salivary duct carcinoma ex pleomorphic adenoma of the minor salivary glands appears to be even rarer. Our case of salivary duct carcinoma ex pleomorphic adenoma of the palate is the first complete report, to our knowledge, in the English-language scientific literature.

PURPOSE: Imaging is important to identify subclinical changes and for treatment planning in patients with osteonecrosis of the jaw (ONJ) exposed to antiresorptive therapy. The aim of this study was to compare the findings at radiography with those at fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) for patients with ONJ related to antiresorptive therapy. MATERIALS AND METHODS: A cross-sectional retrospective analysis of patients with clinically identified ONJ lesions of the mandible was performed. Two imaging modalities were evaluated for each patient: plain radiography (ie, panoramic or periapical) and FDG PET/CT with 1-mm sections. Outcome variables for the radiographic findings were osteolytic and osteosclerotic bone changes. Outcome variables for FDG PET/CT images were localization of FDG uptake. Maximum standard uptake values (SUVmax) of abnormal FDG jaw uptake were recorded, in addition to the mean SUV of the contralateral normal mandible, and used to calculate the target-to-background ratio. Radiographic changes and FDG uptake were classified as local (ie, corresponding to exposed cortical bone) or diffuse (ie, local changes and changes extending beyond the margins of exposed bone) for each imaging technique. Local and diffuse changes detected by each imaging modality were described and the difference in detection was compared with the McNemar test. RESULTS: Twenty-three patients with 25 clinically identified ONJ lesions were analyzed using radiography and FDG PET/CT. Differences were found in how radiography and FDG PET/CT detect local and diffuse changes associated with ONJ. Radiography showed local changes in 17 patients (68%), diffuse changes in 3 patients (12%), and no changes in 5 patients (20%), whereas FDG PET/CT imaging showed local changes in 17 patients (68%) and diffuse changes in 8 patients (32%). The McNemar test indicated that FDG PET/CT imaging was less likely to miss a lesion (P < .001). Mean SUVmax was 6.59, and the mean target-to-background ratio was 5.37. CONCLUSION: The results of this study show that FDG PET/CT detects local and diffuse metabolic changes that may not be represented by plain radiography for patients with ONJ related to antiresorptive therapy. The target-to-background ratio allowed the discrimination between ONJ lesions and background changes. Future studies are necessary to determine whether FDG PET/CT can determine risk and facilitate management of ONJ.

Patients with temporomandibular muscle and joint disorder (TMJD) increasingly seek and receive treatment for their pain with botulinum toxin (BoNTA; botulinum toxin A). Used intramuscularly in therapeutic doses, it produces localised paresis. Such paresis creates risk of reduced bone mineral density, or 'disuse osteopenia'. Animal studies have frequently used BoNTA as a model of paralysis to induce bone changes within short periods. Osteopenic effects can be enduring in animals but have yet to be studied in humans. This is the first study in humans to examine bone-related consequences of BoNTA injections in the masticatory muscles, comparing oral and maxillofacial radiologists' ratings of trabecular bone patterns in the condyles of patients with TMJD exposed to multiple masticatory muscle injection sessions with BoNTA to a sample of patients with TMJD unexposed to masticatory muscle injections with BoNTA. Cone-beam computed tomography (CBCT)-derived images of bilateral condyles were evaluated in seven patients with TMJD receiving 2+ recent BoNTA treatment sessions for facial pain and nine demographically matched patients with TMJD not receiving BoNTA treatment. Two oral and maxillofacial radiologists evaluated CBCT images for evidence of trabecular changes consistent with osteopenia. Both evaluators noted decreased density in all participants exposed to BoNTA and in none of the unexposed participants (P < 0.001). No other abnormalities associated with reduced loading were detected. These findings need replication in a larger sample and over a longer time period, to ensure safety of patients with TMJD receiving multiple BoNTA injections for their pain.

The purpose of this case series is to present the common features of intraosseous mucoepidermoid carcinoma (IMC) of the jaws in plain film and CT imaging. Two oral and maxillofacial radiologists reviewed and characterized the common features of four biopsy-proven cases of IMC in the jaws in plain film and CT imaging obtained from the files of the Department of Oral Radiology, Faculty of Dentistry, University of Toronto, Toronto, Canada. The common features are a well-defined sclerotic periphery, the presence of internal amorphous sclerotic bone and numerous small loculations, lack of septae bordering many of the loculations, and expansion and perforation of the outer cortical plate with extension into surrounding soft tissue. Other characteristics include tooth displacement and root resorption. The four cases of IMC reviewed have common imaging characteristics. All cases share some diagnostic imaging features with other multilocular-appearing entities of the jaws. However, the presence of amorphous sclerotic bone and malignant characteristics can be useful in the differential diagnosis.

Neonatal hemochromatosis (NH) is a severe disease of fetal or perinatal onset, in which iron deposition occurs within hepatic and extrahepatic sites without involving the reticuloendothelial system. Labial minor salivary gland biopsy has been suggested as a diagnostic adjunct in patients suspected of having NH, as hemosiderin accumulates in acinar epithelial cells. Prior to this salivary gland pathology, a diagnosis of NH was often delayed, rendered only after the usual causes of neonatal liver failure had been excluded. Recent studies have shown that early diagnosis and treatment can improve survival. Few cases of salivary gland hemosiderosis in NH have been reported in the literature. A positive finding of salivary gland siderosis on biopsy will expedite care. We report 2 cases of NH, of which a labial salivary gland biopsy supported the diagnosis. The clinical and histological features are presented. The NH literature pertaining to labial salivary gland pathology is reviewed.

Objective: To determine the principal features of dentigerous cysts by a systematic review. Materials and Methods: The relevant literature was identified by searching electronic databases, handsearching key journals, and reference list harvesting. The principal selection criterion was that the study should represent a complete collection of cases. Results: Searches using Medical Subject Heading terms identified more than 80% of systematic reviewincluded reports, but required review of nearly 10,000 Medline abstracts. Although the specific term 'dentigerous cyst' had the highest 'precision' of 1.48%, the non-specific term 'odontogenic cyst' had the highest 'recall' of 58.62%. Some reports displayed a fundamental misunderstanding of the taxonomy and/or histology of dentigerous cyst, even as recently as the 1980s. Five systematic review-included reports were identified by hand-searching relevant journals or by harvesting the reference lists of relevant reports. Thirty published series, covering 4324 cases, were included in the systematic review; 48% were not in the English language. The reports generally included little more than sex, mean age, age range, and site. The 'number of cases of dentigerous cysts per hospital per year' was significantly greater for Asians and Caucasians than for black Africans. The mean ages, given in 3 reports, were significantly older for Caucasians than for black South Africans. The mean age was 28.6 years. There was a 58:42 predilection for men and a 64:36 predilection for the mandible. For the latter, this predilection was significantly greater for Caucasians than for Asians. Among Asians, Chinese people had a significantly greater predilection for the maxilla. Three reports included clinical details and 3 reports included radiological details. Only 1 article reported pain and swelling; dentigerous cysts occurred as an incidental finding in 24% of reports. Conclusions: Medical Subject Heading searches should include a mix of specific and more general terms, and should be used in addition to hand-searches and reference list harvesting. Non-English language reports substantially contribute to the number of cases. There are significant differences in prevalence of various features between ethnic groups. Nevertheless, both lack of detailed reporting and the confusion about nomenclature and histology, until relatively recently, was unexpected for this hitherto supposedly well-understood lesion. The radiology component of the systematic review-included reports is almost non-existent in comparison to systematic reviews conducted for other lesions