This patient is a 71-year-old male with a left neck adenopathy and his lymph node biopsy was positive for metastatic squamous cell carcinoma. Conventional evaluation of the head and neck with physical examination, endoscopy and CT scan demonstrated no identifiable site of primary neoplasm.

The whole body PET can demonstrates two foci of hypermetabolic activity in the left neck consistent with nodal metastases (long arrow). PET scan also identified a focus of hypermetabolism in the floor of the mouth (short arrow).

Using the PET scan result, the patient's physician identified the primary squamous cell cancer in the floor of the mouth. Its histology was similar to that found in the left neck nodes. The patient underwent resection of primary neoplasm and nodal metastases followed by radiation therapy.

PET can identification of the primary head and neck neoplasm and residual nodal metastases allowed local control of known disease with surgery and radiation therapy.