Granulocyte colony-stimulating factor-producing carcinoma of unknown primary site

Granulocyte colony-stimulating factor (G-CSF)-producing nonhematopoietic malignancies have been reported in various organs and are associated with a poor clinical outcome. Moreover, carcinoma of unknown primary site (CUP) is an uncommon malignancy that occurs in about 2-6% of cancer patients. CUP also has a poor prognosis due to its missing profile. Since both G-CSF-producing carcinoma and CUP are rare, G-CSF-producing CUP (GCSF-CUP) is considered to have an even poorer prognosis and is seldom encountered. Herein, we report the case of a GCSF-CUP patient. A 75-year-old man was admitted to our hospital complaining of cervical lymphadenopathy. Multiple bulky lymph nodes without a primary site were revealed by image analysis. His complete blood count showed leukocytosis, and his blood chemistry panel indicated highly elevated levels of G-CSF. Although the patient was treated with combination chemotherapy of carboplatin, paclitaxel, bevacizumab and erlotinib, he died of intestinal perforation due to tumor invasion 23 days after the start of the therapy. An autopsy confirmed that the tumor was positive for anti-G-CSF antibody, but the primary site was still not detected.