Tongue Base Cancer

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

Patient Presentations:

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

Criteria for “Active Malignancy”: 

As previously addressed (here), uniform and symmetric (non-focal & non-eccentric) FDG uptake along the base of the tongue typically represents normal lymphoid tissue involving Waldeyer’s ring, even if intensely avid.

When a fairly complete hypermetabolic Waldeyer’s ring is seen, the uptake along the base of the tongue will nearly always be normal. A complete ring, however, is often not present in normal patients.

There are 3 presentations that warrant close attention:

• 1. Symmetric & uniform uptake, accompanied by significant soft tissue fullness on the co-registered CT images: 
  • Even though the majority of such cases do not represent malignancy, we report:

  • “Prominent, intensely-avid soft tissue density is noted along the base of the tongue (SUV 4.6).  While a neoplastic process cannot be entirely excluded, its symmetric and uniform uptake suggests this is likely physiologic or inflammatory in nature.”

• 2. Focal, asymmetric/eccentric uptake along a portion of the tongue base, with or without an associated soft tissue lesion on the co-registered CT images:   
  • This appearance should always raise a concern for a primary tongue base cancer, and requires direct visualization by a clinician.

  • “Prominent, eccentric and intensely-avid soft tissue density is noted along the left base of the tongue (SUV 4.6). Direct visualization is recommended in this case to exclude a primary tongue base cancer.

• 3. Well-defined FDG-avid soft tissue mass: An obvious diagnosis.

CAVEAT: 

For all 3 of these presentations, the presence of associated hypermetabolic cervical nodes dramatically increases the likelihood of malignancy (and the confidence of your reporting).