Abstract
Purpose
1) To determine SUVs and PET/CT characteristics of Warthin’s tumors in patients presenting to a head and neck cancer clinic.
2) To analyze the impact of PET/CT on the clinical course of these patients.
Materials and methods
This is a single-institution retrospective analysis of patients with proven Warthin’s tumors who underwent PET/CT done at or near the time of diagnosis and presented to a head and neck cancer practice. Data were obtained from the electronic medical records of these patients and the imaging and pathology databases.
Results
Six patients with Warthin’s tumor met the criteria for and form the study cohort. Three patients had bilateral tumors. The SUVs for Warthin’s varied from 3.4 to 16.1 in these patients, with an average of 7.8 and these SUVs were higher for Warthin’s than for the cancers. These findings on PET/CT in this group required additional workup of all patients and required FNA, surgery or SPECT-CT to confirm the diagnosis.
Conclusion
Although it is known that Warthin’s tumor may be hypermetabolic on PET, this finding in the parotid or neck on PET/CT alters the evaluation and treatment of head and neck cancer patients and patients with cancers outside the head and neck by raising the concern about metastatic disease or multiple primary cancers. In other patients, PET/CT obtained for other reasons may prompt concern about incidental malignancy. This series specifically characterizes clinical features, SPECT-CT and FNA findings that can help reinforce the diagnosis of Warthin’s and facilitate management.
1
Introduction
Positron Emission Tomography using F DeoxyGlucose (FDG-PET) was introduced in the 1970’s and Townsend and colleagues are often credited with its current impact . PET has gained popularity for a number of applications, several of which may be applied to head and neck tumors. FDG-PET scans have multiple applications and more recently fusion of PET with computed tomography (PET/CT) has become popular. The applications of FDG-PET and PET/CT include: evaluation of brain blood flow and metabolic activity , determination of blood flow to heart muscle and evaluation of the heart for areas of ischemia and infarction, mapping of normal brain and heart function for research purposes, and detection of cancer at various sites in the body. For diagnosis and treatment of cancer, including head and neck cancers, the principal uses are for detection of primary lesions and quantitation of the metabolic activity of these lesions, evaluation for sites of regional and distant metastasis, and post-treatment surveillance for residual and recurrent lesions .
PET uses a radioactive tracer (FDG) and the concentration of tracer imaged then gives tissue metabolic activity, in terms of regional glucose specific uptake value (SUV). Many malignant lesions have a high metabolic rate, and most will actively accumulate the tracer with standard uptake values (SUVs) of 3.0 or greater . In general, malignant lesions must be about 8 mm in diameter to be visible on PET scan however the size of a detectable lesion depends also on its inherent metabolic activity . A significant pitfall of PET scanning is that false positives do occur. Inflammatory lesions throughout the body have been shown to be FDG avid in many circumstances requiring an evaluation of these findings in the pretreatment workup, which can even delay cancer treatment in some situations . Other false positives can be produced by muscle activity, vocal cord paralysis, brown adipose tissue, lymphoepithelial tissue and high contents of saliva. Knowledge of these false-positives has led to refinements in PET/CT techniques and interpretation .
Our experience and the review of the literature have identified a number of false positives when imaging the neck. Data from prior studies seem to indicate that PET scan is neither sensitive nor specific enough to be used to evaluate the clinically negative neck in head and neck cancer . Nevertheless, PET and PET/CT will identify some patients with occult adenopathy. While sentinel node mapping literature shows that the sensitivity of PET is inferior to the surgical staging , selective neck dissection is also imperfect as approximately 10% of pathologically negative neck dissections may be found to have microscopic metastases when subjected to serial sectioning and immunohistochemisty . PET/CT is very useful and it is unfortunate that the false positives have resulted in some surgeons avoiding the study to prevent delays in treatment that result from the need to further evaluate these other findings. This study addresses one of the specific positive findings in a series of patients seen in a head and neck cancer clinic, namely the finding of Warthin’s tumors that are hypermetabolic.
The objectives of the present study were to identify patients with Warthin’s tumor who underwent PET/CT and determine the SUVs and PET/CT characteristics of Warthin’s tumors in this cohort of patients. In addition, we analyzed the impact of a PET-positive Warthin’s on the further workup and management of this group of patients. We believe that this is important as part of the evaluation of “false” positives in PET/CT.
2
Methods and materials
This is a single-institution retrospective study involving patients with proven Warthin’s tumors over a 5-year period. Patients were identified within our cancer database and the study was approved by the West Virginia University Institutional review board for protection of human subjects. Patients who had a PET/CT done at or near the time of diagnosis of the Warthin’s tumor were included.
A review of the medical records of patients undergoing parotidectomy, neck dissection and/or fine needle aspiration of a parotid lesion at our institution between 2005 and 2010 was undertaken. Patients were evaluated for the following parameters: history of tobacco use, specifically smoking, history and specifics of cancer diagnosis, cytologic or pathologic diagnosis of Warthin’s tumor, maximum SUV of Warthin’s tumor on PET and tumor characteristics including location and size of the primary tumor if present and any Warthin’s tumors.
2
Methods and materials
This is a single-institution retrospective study involving patients with proven Warthin’s tumors over a 5-year period. Patients were identified within our cancer database and the study was approved by the West Virginia University Institutional review board for protection of human subjects. Patients who had a PET/CT done at or near the time of diagnosis of the Warthin’s tumor were included.
A review of the medical records of patients undergoing parotidectomy, neck dissection and/or fine needle aspiration of a parotid lesion at our institution between 2005 and 2010 was undertaken. Patients were evaluated for the following parameters: history of tobacco use, specifically smoking, history and specifics of cancer diagnosis, cytologic or pathologic diagnosis of Warthin’s tumor, maximum SUV of Warthin’s tumor on PET and tumor characteristics including location and size of the primary tumor if present and any Warthin’s tumors.
3
Results
Six patients with Warthin’s tumor who met the criteria for the study had adequate PET/CT images. All six of these patients had a history of smoking tobacco. Four of the patients had bilateral tumors. Three of the patients had malignancy, which prompted the PET/CT, and three had other indications for PET/CT, which were approved by third party payors. The SUVs for Warthin’s varied from 3.4 to 16.1 in these patients, with an average of 7.8 and these SUVs were higher for Warthin’s than for the cancers. None of the patients have developed malignancy in the areas where we made a diagnosis of Warthin’s with a minimum of 5 year follow up. Table 1 shows the key features of the six cases which are described in detail in this article.
| Patient | Primary DX | PET/CT SUVMAX | FNA | Path | Tc-99 | Location | Bilateral | Pack-years smoking |
|---|---|---|---|---|---|---|---|---|
| 1 | Bilateral Laryngoceles | 7.0/7.3 lung 12.3 | + | NA | + | parotid/?neck | Y | 80 |
| 2 | Stroke | 16.1 | + | NA | + | parotid | P | 30 |
| 3 | Supraglottic Cancer | 6.7 | − | + R | + L | parotid | Y | 50 |
| 4 | Lung CA | Not avail | + | NA | NA | parotid | N | 60 |
| 5 | Left Neck Mass | 3.4 | Suspicious for SCCA | + | NA | parotid | Y | 50 |
| 6 | Vascular Disease | 6.5 | + | NA | NA | neck | N | 50 |
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