Granulocyte-colony stimulating factor (G-CSF)-producing carcinomas have been reported in various organs and are known to be associated with a poor clinical prognosis. Carcinoma of unknown primary site (CUP) is an uncommon malignancy that accounts for about 1%–4% of all head and neck malignant neoplasms, and also has a poor prognosis. We report a very rare case of G-CSF-producing CUP (G-CSF-CUP), which is considered to have an even poorer prognosis.
A 67-year-old woman was admitted to our hospital with a left neck mass.
Laboratory examination revealed a high serum level of G-CSF. FDG PET/CT showed intense FDG uptake in the left cervical mass and the spine. The site of origin of the primary tumor could not be identified despite thorough diagnostic evaluation. Therefore, we made the diagnosis of G-CSF-CUP of the head and neck. The patient was treated by surgical resection of the neck mass and postoperative chemoradiation therapy, following which the serum levels of G-CSF returned to normal range and the FDG accumulation in the spine on PET decreased. At present, more than 21 months since the surgery, the patient remains alive with no evidence of recurrence.
