Soft tissue aspiration cytopathology - Diagnostic accuracy and limitations

BACKGROUND. Fine-needle aspiration (FNA) biopsy as a diagnostic modality fo r the pathologic evaluation of soft tissue neoplasms and non-neoplastic sof t tissue mass lesions is uncommon and controversial. This procedure contras ts with more traditional diagnostic methods such as marginal excision, inci sional (open) biopsy, or even core biopsy to procure tissue from somatic si tes. METHODS. The authors reviewed the results of cytopathologic diagnoses obtai ned by fine-needle aspiration biopsy over a consecutive 11-month period in patients that presented primarily with a palpable soft tissue mass. A few p atients with deep non-palpable soft tissue masses also were evaluated by ra diologically guided FNA. Cytopathologic diagnoses were verified by differen t means including tissue examination either by concurrent cell block or sub sequent surgical biopsy, flow cytometry, clinical outcome, or repetition of the FNA procedure. Patients were followed for a minimum of one year to eva luate the mass clinically, to determine whether any further therapy was adm inistered, and to assess disease status. RESULTS. Eighty-two aspirates were pet-formed without complications from 77 patients ranging from 12-88 years of age (mean = 50 yrs.) with men outnumb ering women 1.5:1. Soft tissue masses were most common in the extremities ( 41 cases), followed by the trunk (34 cases), retroperitoneum (5 cases), and head and neck (2 cases). Fine-needle aspirates were diagnosed as malignant in 42 (51%), benign in 32 (39%), nondiagnostic in 6 (7%), and atypical in 2 (2%) cases. Malignant aspirates were comprised of 24 sarcomas (57%), 9 ca rcinomas (21%), 6 malignant lymphomas (14%), and 3 melanomas (7%). Twenry-t wo aspirates (52%) had an initial diagnosis of malignancy, whereas 18 (43%) represented metastatic and 2 (5%) recurrent neoplasms. Confirmation of the cytopathologic diagnosis was by concurrent or subsequent tissue examinatio n in 57%, flow cytometry in 5%, clinical outcome in 34%, and repeat aspirat ion in 4%. One false negative and no false positive diagnoses were issued f or a sensitivity and specificity of 100% and 97% respectively in distinguis hing benign and malignant lesions by FNA. Of the malignant aspirates, 83% c ould be subtyped whereas 72% of benign aspirates were correctly subtyped. F or primary soft tissue sarcomas, 12 of 19 (63%) were accurately subtyped. I n 48% of cases a concurrent cell block was obtained and found diagnosticall y useful in 54% of them. CONCLUSIONS. Aspiration cytopathology of soft tissue mass lesions using FNA biopsy can be an accurate and minimally invasive method for the initial pa thologic diagnosis of primary benign and malignant soft tissue masses, for the pathologic confirmation of metastatic tumors to soft tissue, and for th e documentation of locally recurrent soft tissue neoplasms. FNA cytopatholo gy is capable of specifically subtyping a large percentage of primary and m etastatic son tissue tumors if cellular material either in the form of a ce ll block or flow cytometry is obtained in addition to cell smears. Cancer ( Cancer Cytopathol) 2000;90:292-8. (C) 2000 American Cancer Society.