A 37-year-old woman with ovarian and rectal cancer underwent a [18F]-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) to evaluate the responses after the completion of her chemotherapy. Approximately one year before the [18F]FDG PET/CT, she presented with abdominal pain and the abdominal computed tomography (CT) showed right ovarian and rectal masses. She received a total abdominal hysterectomy with bilateral salpingo-oophorectomy, which revealed an endometrioid adenocarcinoma of the right ovary and a subsequent low anterior resection, which also revealed a poorly differentiated adenocarcinoma. Her adjuvant chemotherapy ended approximately two months before the [18F]FDG PET/CT.
The [18F]FDG PET/CT did not show evidence of [18F]FDG-avid disease in her abdominopelvic cavity. Although the patient denies any symptoms related to the nasal cavity and upper airway, such as nasal congestion, runny nose, epistaxis, pain, or growth sensation, the PET/CT revealed an [18F]FDG-avid expansile ossified lesion in the left palatine process of the maxilla. The lesion had a bulging contour in the adjacent nasal and oral cavities with a maximum standardized uptake value (SUVmax) of 10.3 (Fig. 1). Subsequently, the surgeon performed a fiber-optic laryngoscopy with tumor excision using an oral approach. The histopathology of the mass was consistent with ossifying fibroma (Fig. 2).
Ossifying fibroma is a rare entity with a constantly changing classification [1]. Since the 2017 World Health Organization (WHO) classification of head and neck tumors, ossifying fibroma has been classified as a type of fibroosseous lesion [2]. Increased [18F]FDG uptake has been reported in several fibroosseous lesions, including non-ossifying fibromas, fibrous cortical defects, cortical desmoids [3], ossifying fibromas associated with hyperparathyroidism-jaw tumor syndrome [4], juvenile psammomatoid ossifying fibromas [5]. According to previous reports, the [18F]FDG uptake in fibroosseous lesions did not correlate with the size of the lesions and did not subside in follow-up [18F]FDG PET/CT. Therefore, some researchers suggested that these lesions should be characterized based on their CT appearance, rather than on [18F]FDG uptake [6].
The incidence of [18F]FDG-avid foci is increasing with the more widespread use of PET/CT. In the head and neck region, most common incidental [18F]FDG uptakes were seen within the thyroid gland, followed respectively by the pituitary gland, the parotid gland, and the naso-oropharynx. Pencharz et al. [7] suggested that proper management of incidental [18F]FDG uptake should depend on location, and standardized uptake values (SUV) were useful only in some locations.
No consensus guideline has been established on the management of incidental [18F]FDG uptake in the oral and sinonasal regions. It was reported that the most common cause of incidental [18F]FDG uptake in these regions on PET/CT was chronic rhinosinusitis. Unfortunately, malignancy could account for up to 27% of incidental uptake in the sinonasal region [8] and up to 14% of incidental uptake in the palatine tonsils [9]. Since malignancy was responsible for a substantial fraction of incidental oral and sinonasal uptake, additional investigation could be warranted in some patients with incidental oral and sinonasal uptakes based on the clinical context, type of uptake (diffuse vs. focal), and CT appearances.
Conflict of interest
The authors declare no conflicts of interest.
