G-CSF producing oral carcinoma with diffuse uptake of FDG in the bone marrow: A case report.

A 78-year-old male patient was referred to the Department of Oral Surgery, Hokuto Hospital (Obihiro, Japan) for painless swelling on the left neck and tongue. Histopathological examination of a biopsy specimen resulted in a diagnosis of squamous cell carcinoma of the tongue. Imaging examinations revealed cervical lymph node metastases on both sides, along with diffuse uptake of 18F-fluorodeoxyglucose (FDG) in the bone marrow of the spine and pelvis. Hematologic tests revealed an increased white blood cell (WBC) count and serum concentrations of granulocyte colony stimulating factor (G-CSF). These findings suggested a G-CSF producing tumor, with fluctuations of WBC count, serum G-CSF concentration, and FDG uptake in the bone marrow, associated with tumor shrinkage and enlargement, an indicator of tumor status.