Tonsillar (Palatine) Carcinoma

• Fast Facts:  Covered here.
• Indications for PET/CT: Covered here.
• Imaging Protocol: Covered here.

Patient Presentations:

• The majority of patients with tonsillar carcinoma have a biopsy-proven diagnosis prior to PET/CT scanning. In such cases, any increased FDG uptake involving a tonsil typically represents the cancer (prior to therapy).
• Many patients will present with the diagnosis of metastatic SCCA of unknown primary.  A tonsillar primary must be excluded in these patients.
• Lastly, on rare occasion, an incidental tonsillar carcinoma cancer will be identified.

Symmetric, Bilateral Tonsillar Uptake:

The palatine tonsils frequently demonstrate significant metabolic activity. 

Bilateral and fairly symmetric FDG-uptake in non-enlarged palatine tonsils is typically a normal finding, and is usually not mentioned in a report.

Bilateral and fairly symmetric FDG-uptake in enlarged palatine tonsils is nearly always inflammatory in nature (although can be seen with lymphoma).

Unilateral FDG-Avid Tonsil (or Relative Increased Avidity of One Tonsil): 

Special care is required when assessing the incidental finding of a unilateral hot tonsil (or relative increased uptake within one tonsil) — even though most unilateral hot tonsils are benign. Proposed techniques for assessment have included SUV threshold cutoff values, metabolic tumor volume assessment, and SUV ratios.

Unfortunately, it is advisable to raise at least a degree of concern for most FDG-avid unilateral tonsillar findings.   The level of suspicion, of course, depends on the presentation.  

At PETCTMD, we utilize the following practical approach for the incidental finding of a unilaterally FDG-avid tonsil:

1. NON-ENLARGED AND:
   • Unilaterally Avid (≥ Liver Uptake)
   • OR
   • Uptake “Unquestionably” > Contralateral Tonsil

We typically report, “While this uptake is typically physiologic or inflammatory in nature, direct visualization may be of diagnostic value, if clinically warranted.”

(If the uptake is < liver uptake, we presume the metabolic activity to be physiologic or inflammatory)

2. UNILATERALLY ENLARGED AND:
   • Unilaterally Avid (≥ Liver Uptake)
   • OR
   • Uptake “Unquestionably” > Contralateral Tonsil

We typically report, “While its increased size and increased metabolic activity may be inflammatory in nature, direct visualization may be warranted to exclude a neoplastic process in this case.” 

3. Any Unilateral Tonsillar Uptake Associated with Hypermetabolic Cervical Nodes: 

Clearly, the presence of hypermetabolic cervical nodes dramatically increases the likelihood of malignancy (and the confidence of your reporting).