Clinical Efficacy of FDG‐PET/CT in Head and Neck Adenoid Cystic Carcinomas

Objective Positron emission tomography/computed tomography (PET/CT) with fluorine‐18‐2‐fluoro‐2‐deoxy‐D‐glucose (FDG) of salivary malignancies is variable, thus unreliable for staging/surveillance. For adenoid cystic carcinomas (ACC), data is limited regarding FDG uptake. The objective is to characterize PET/CT and its ability to detect primary disease/tumor recurrence in patients with head and neck ACCs (HNACCs). Method Ten‐year retrospective study of 25 patients diagnosed with HNACCs. Eleven patients (8 women; age 33‐65 years at time of diagnosis) were referred for whole‐body FDG‐PET/CT. Secondary imaging modalities were also acquired. Fifteen tumor sites (primary and metastatic foci) were evaluated. Histological disease was confirmed by biopsy and surgical pathology. Results Of those referred for PET/CT, 81.8% (9/11) had primary disease foci detected and 22.2% (2/9) had distant metastasis. In one patient with metastatic disease, cavernous sinus disease was detected on MRI and not appreciated on PET/CT but was consistent with MRI in detecting disease foci of the nasal dorsum and lung. In one patient with base of the tongue ACC, PET/CT accurately detected cervical lymph nodes suspicious for malignancy not detected on CT scan. On MRI, another patient treated for nasal cavity ACC had what appeared to be disease recurrence, not appreciated on PET/CT and was confirmed as a pyogenic granuloma. Conclusion In HNACCs, FDG‐PET/CT is useful for preoperative evaluation of initial/recurrent disease foci and disease staging for treatment strategy; thus it shouldn’t be excluded as a method of patient evaluation.