Dedifferentiated liposarcoma with leukocytosis. A case report of G-CSF-producing soft-tissue tumors, possible association with undifferentiated liposarcoma lineage

BACKGROUND Granulocyte-colony-stimulating factor (G-CSF) functions as a hematopoietic growth factor and it is responsible for leukocytosis. G-CSF-producing tumors associated with leukocytosis include various types of malignancies. CASE PRESENTATION We report the case of a 72-year-old man with dedifferentiated liposarcoma characterized by dedifferentiated components of malignant fibrous histiocytoma (MFH)-like features in addition to well-differentiated lipoma-like liposarcoma, arising from his upper arm. Preoperative laboratory data showed leukocytosis (103,700/mul). The serum level of G-CSF was also elevated (620 pg/ml [normal, <8 pg/ml]). Nine days after the surgery, the leukocytosis was relieved (WBC; 6,920/mul) and the elevated serum G-CSF level was significantly decreased (G-CSF; 12 pg/ml). One month after the surgery, leukocytosis gradually began to appear again. Three months after the surgery metastatic lung lesions were confirmed, and the patient subsequently died of respiratory problems. In the English literature regarding soft-tissue tumors with leukocytosis, including the current case, we could review a total of 6 cases of liposarcoma with leukocytosis. The subtype of these 6 liposarcoma cases was undifferentiated liposarcoma, comprising dedifferentiated liposarcoma in 4 cases and pleomorphic liposarcoma in 2 cases. CONCLUSION Since the only other soft-tissue tumor that was associated with leukocytosis was MFH, and since MFH is characterized by the absence of any specific differentiation, we would like to propose a possible association between G-CSF-producing soft-tissue tumors and an undifferentiated liposarcoma lineage, such as dedifferentiated liposarcoma or pleomorphic liposarcoma.