18F–FDG PET/CT scan confirmed by pathology findings in a singular case of squamous cell carcinoma of the epiglottis

Background Only about 1% of all head and neck lateral or paramedian cancers described in the scientific literature shows, in staging, contralateral cervical adenopathy without ipsilateral pathological involvement of lymph nodes. Case Presentation This case is one of them, in which 18F–FDG PET/CT scan is confirmed by pathology findings, and has correctly identified all metastatic disease foci. Conclusions To date, PET/CT is not recommended in head and neck cancer staging. However, the use of PET/CT in head and neck cancer staging can define possible metastatic disease foci, clarify c.e. CT suspicious findings and, in some cases, change the TNM stage, with a strong prognostic and therapeutic impact.

cervical lymph nodes (white arrow), both some small right lateral cervical lymph nodes with contrast enhancement (red arrow).
Overall, in the radiological report, c.e.CT was doubtful for ipsilateral adenopathy. Staging continued with a whole body [18F]-FDG PET/CT to assess possible metastatic disease foci and to define the nature of the ipsilateral cervical lymph-nodes.
A whole-body PET scan was acquired, 3 min per bed position, one hour after the injection of a standard activity (3,5 MBq/Kg) of 18F-FDG. It was also performed a lowdose CT for the attenuation correction (120 kV, 80 mA, 0.8 s per rotation, thickness 3,75 mm).
Histopathology results showed a squamous cell carcinoma of the right lingual epiglottis side, no malignant cells in the right lateral cervical lymph nodes, while metastatic cells in the left lateral cervical lymph nodes were detected (pT1-N2b).

Discussion
[18F]-FDG PET/CT report was confirmed by pathology, identifying the primary epiglottic carcinoma and addressing as metastatic just the contralateral lymph nodes.
[18F]-FDG PET/CT properly assessed as negative the ipsilateral lymph nodes that were suspected to be metastatic at c.e.CT.
The presence of the contralateral lymph node metastasis without ipsilateral lesion, is a very rare event since it may occur in about 1% of all head and neck cancers (Rucci et al., 1990); in this case, the primary mass on the right lingual epiglottis side was very close to midline, so we could have expected, at least, a bilateral cervical involvement, but not a solitary contralateral adenopathy.
[18F]-FDG PET/CT scan confirmed, in this patient, to be an accurate method to stage head and neck cancer.
However, to date there is not a single staging modality that could spare these patients a bilateral neck dissection. Patients could also benefit from a sentinel node investigation in order to identify the primary lymphatic way and, if the lymphatic drainage side is same as the pathological nodes identified by PET, only contralateral dissection may be considered.
At this time, [18F]-FDG PET/CT is considered an important imaging modality in the evaluation of squamous cell carcinoma of the head and neck (Quon et al., 2007), especially for the detection of regional nodal metastasis (Sun et al., 2015;Schöder & Yeung, 2004).
However, the indications to PET scan, in head and neck cancer staging, are not completely exploited, compared to its application in restaging, assessment after-surgery, radiotherapy and follow-up.

Conclusion
Whole body [18F]-FDG PET/CT, used in staging, can identify metastatic foci, clarify c.e.CT suspicious findings and, in some cases, change the TNM stage, with a strong prognostic and therapeutic impact.