[Cytology of soft tissue tumors]

In the diagnosis of soft tissue tumors, an incomplete biopsy for malignancy interferes with subsequent therapy. Therefore, we perform fine needle aspiration cytology (FNAC) for soft tissue tumors and consider the following four issues: 1) Is the tumor benign or malignant?; 2) In malignancy, is the tumor primary or metastatic? Furthermore, if possible; 3) In a primary malignant tumor, the histological type and degree of malignancy; 4) In a metastatic malignant tumor, the histological type and the primary site. In FNAC, we diagnose soft tissue tumors based on the pattern of cytological findings, such as small round cells, pleomorphic cells, spindle cells, and epithelioid cells, and furthermore based on the findings of the background, such as mucin, vessels, multinucleated giant cells, and inflammatory cells while referring to clinical information. In soft tissue tumors that are difficult to diagnose only by cytology, immunochemical staining for multiple antibodies using the cell block method and/or cell transfer method is useful to make a definitive diagnosis. If necessary, rapid cytological diagnosis is currently performed for soft tissue tumors in our department.