SLR - June 2010 - Kurt Glesne
Reference:
Ng, V.Y., Thomas, K., Crist, M., Wakely, P.E., Mayerson, J. Fine Needle Aspiration for Clinical Triage of Extremity Soft Tissue Masses. Clinical Orthopaedics and Related Research. (2010) 468: 1120-1128
Scientific Literature Reviews
Reviewed by: Kurt Glesne, DPM
Residency Program: Florida Hospital East Orlando
Podiatric Relevance:
Understanding the diagnostic modalities and their associated value in evaluating soft tissue masses in the lower extremity is critical for ensuring proper care of such patients that present to the podiatric physician. This article evaluates the effectiveness of fine needle aspiration as an alternative to open biopsy or needle core biopsy for evaluating soft tissue masses. Specifically, the effectiveness of diagnosing malignancy with fine needle aspiration was assessed.
Methods:
A retrospective review of 432 cases treated by a primary musculoskeletal oncologist in an office based setting who received fine needle aspiration (FNA) for palpable soft tissue masses was undertaken. The study included only patients with soft tissue masses that were palpable and did not require radiographic guidance for FNA. The results of the fine needle aspiration cytology (FNAC) were interpreted by the head cytopathologist or another experienced musculoskeletal pathologist. Pediatric soft tissue sarcomas were excluded from the study. The study group consisted of 213 male and 219 female patients. Mean age of the patient's was 51.8. The locations of FNA included the thigh (107), leg (57), foot and ankle (40), knee (37), arm (34), hand and fingers (28), forearm (24), shoulder (23), and back (11). Pathology reports acquired from open biopsies or resections were compared with the initial FNAC findings. The decision to perform definitive treatment or a secondary biopsy was made by the primary musculoskeletal oncologist. Subtyping and cytomorpholigic groupings were based on the recommendations of Association of Directors of Anatomic and Surgical Pathology. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for all patients who had FNAC. The accuracy of grading and subtyping of malignant lesions was calculated based on cases with a FNA diagnosis and histopathologic confirmation.
Results:
268 patients were subtyped as benign, 35 patients indeterminate, and 129 malignant after FNAC. In patients with definitive tissue verification, the sensitivity and specificity for detecting malignancy with FNAC was 88.9% and 84.4% respectively. PPV was 95.1% and NPV was 96.4%. 140/268 patients with a benign lesion had a subsequent definitive tissue diagnosis after FNA, of these 134/140 were confirmed as benign, 6/140 were determined to be malignant neoplasms. Of the malignant cases with tissue verification (101), FNAC correctly identified 95% of the cases, with five false positives. Of the 268 cases of benign FNAC, definitive treatment was rendered in 218 cases (81.3%). In the indeterminate FNAC group (35), the definitive treatment plan was rendered in 15 cases (42.9%), the remaining 20 required additional verification with either open biopsy, needle core biopsy, or definitive resection. Overall 24.8% of all patients required a secondary biopsy before pursuing a definitive treatment plan.
Conclusions:
FNAC is a highly effective diagnostic modality for detecting malignancy in patients presenting with a palpable soft tissue mass. Open incisional biopsy still remains the gold standard for providing ample tissue for analysis, however it has substantial drawbacks that must be incorporated into the decision making process including anesthetic complications, wound healing problems, infection, and tumor seeding. In comparison, FNA is less painful, provides expedient patient triage, and is more cost effective. The sensitivity, specificity, PPV, and NPV of FNAC in this study is comparable to other published rates. Without an experienced on-site cytopathologist to interpret the FNAC and determine if additional sampling is necessary, the advantage of FNAC is lost. The clinician must also understand that sampling error and misdiagnosis can occur if cells are aspirated from overlying structures. If the lesion contains cystic, hemorrhagic, or necrotic areas, misrepresentative samples may have been aspirated. Close multidisciplinary collaboration with an experienced cytopathologist can determine when a secondary biopsy is appropriate.