Fine needle aspiration for clinical triage of extremity soft tissue masses.

Background: Fine needle aspiration cytology (FNAC) is a rapid and low-morbid alternative to open biopsy or needle core biopsy for soft tissue masses. Numerous reports describe its use with metastatic or recurrent lesions, but FNAC is less accepted for primary lesions.

Questions/purposes: We wished (1) to estimate the sensitivity, specificity, and positive and negative predictive values of FNAC for diagnosing malignancy; (2) to estimate the accuracy of subtyping and grading.

Methods: We retrospectively examined the diagnostic accuracy and clinical effectiveness of office-based FNAC performed by a trained pathologist on 213 females and 219 males (mean age, 51.8 years) who presented with a palpable soft tissue mass to one musculoskeletal oncology clinic between 2002 and 2008.

Results: The FNAC was reported as benign in 62.0%, indeterminate in 8.1%, and malignant in 29.9%. A second technique, such as needle core biopsy or open biopsy, was performed for 24.8% of lesions before a definitive treatment plan was rendered. Final tissue confirmation by open biopsy or resection was available for 52.2% of benign FNAC and 78.3% of malignant FNAC. Sensitivity, specificity, and positive and negative predictive values for detecting malignancy with either histopathologic confirmation or clinical followup were 89.2%, 89.8%, 96.1%, and 98.1%. There were seven sampling and nine interpretation FNAC errors in determining the nature of the lesion. Subtyping and grading for malignant lesions were 77.2% and 95.2% accurate, respectively.

Conclusions: FNAC is effective for initial triage and treatment selection at tertiary referral centers with close collaboration among the surgeon, pathologist, and radiologist.

Level Of Evidence: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.