We retrospectively searched the medical records of all patients seen by the primary musculoskeletal oncologist (JM) at the adult office of the Arthur G. James Comprehensive Cancer Center at The Ohio State University between September 2002 and April 2008 to identify patients who received a FNA. The study group included only patients with soft tissue masses that were palpable on physical examination and that did not require radiographic guidance for FNA. Results of all FNAC specimens were interpreted by the head cytopathologist (PEW) or another experienced musculoskeletal pathologist (CM). Pathology reports from open biopsies and mass resections were accepted from all attending physicians in the pathology department. We believe FNAC plays a different role in the management of pediatric soft tissue sarcomas, and we therefore excluded patients seen in the pediatric office. Because of the specific chemotherapeutic protocols for Ewing sarcoma, rhabdomyosarcoma, and osteosarcoma, histologic subtyping is necessary for appropriate selection of therapy. FNAC is more accurate in pediatric sarcomas in this regard [15
]. We identified 459 cases of FNA. Twenty of these (4%) were excluded because the FNAC had been interpreted by a nonmusculoskeletal pathologist. Seven were excluded because the patient did not have definitive tissue verification of their FNA, did not return for followup, and could not be reached by telephone. The final study group consisted of 432 FNAs performed on 213 male and 219 female patients (Fig. ). The mean age of the patients at the time of FNA was 51.8 years (range, 13–91 years). The most common locations were the thigh (107), leg (57), knee (37), arm (34), hand and fingers (28), forearm (24), foot and ankle (40), shoulder (23), and back (11). The FNAC diagnosis was benign in 268 of 432 (62.0%) cases, malignant in 129 (29.9%), and nondiagnostic or indeterminate in 35 (8.1%) (Fig. ). The mean ages in each group were 48.7 years, 58.3 years, and 51.4 years, respectively. Proceedings were in accordance with the approved Ohio State University Institutional Review Board, application 2003C0058.
The study design is shown in this flow chart. Bx = biopsy; prn = as needed.
In all cases, a pathologist discussed clinicoradiographic findings with the surgeon, examined the patient, and performed a percutaneous FNA. One-, 1.5-, or 2-inch long 21- or 22-gauge needles connected to a 20-mL syringe was inserted without local anesthesia at the apex of the lesion or at a location specified by the orthopaedic oncologist to optimize future resection. Using firm suction and short, rapid strokes, an average of three separate passes was made. With each pass, the needle was angled in a different direction to sample as much of the mass as possible. Aspirated material was expelled onto glass slides and a second glass slide was used to make conventional smears. The needle was rinsed in a balanced salt solution after each pass for additional study: flow cytometry, paraffin-embedded cell block, or fluorescent in situ hybridization. For initial assessment, several slides were air-dried and stained with a Romanowsky stain. The remainder subsequently was rehydrated and stained using a modified Papanicolaou method. Within 20 minutes, a preliminary reading was rendered.
All pathology reports for tissue specimens acquired from open biopsies or resections were compared with the initial FNAC findings. Because the reliability of NCB compared with FNAC is controversial, NCB was not used for definitive verification of FNAC for the purposes of this study [4
]. Subtyping and cytomorphologic groupings were based on the recommendations of Kilpatrick et al. [14
] and Singh et al. [29
] and Fletcher et al. for the Association of Directors of Anatomic and Surgical Pathology (ADASP) [10
] (Table ).
Grading of soft tissue sarcomas based on subtype/cytomorphologic grouping on fine needle aspiration cytology*
All decisions to proceed with definitive treatment or to perform a secondary biopsy were made by the primary musculoskeletal oncologist (JM) based on clinical judgment, radiologic findings, and cytologic findings. Rarely was a repeat FNA performed if the initial FNAC was nondiagnostic.
For patients who did not have histopathologic followup of a benign FNAC, attempts were made for this study to contact them or their primary physician by telephone to detect any potential misdiagnoses. For the cases in which the FNAC report was discrepant from the final pathology report, the head musculoskeletal pathologist (PEW) reviewed the cytology slides and compared them with the definitive tissue sample. Error was classified as sampling error if the FNAC slide did not contain material indicative of the actual pathology. Otherwise, it was deemed an interpretive error.
In the benign FNAC group (Table ), 123 of 268 (46%) patients had surgical removal of their soft tissue mass. The other 145 were managed nonoperatively and were instructed either to follow up on an as-needed basis or to return for repeat imaging and serial examination. For patients told to follow up as needed, successful telephone contact was made at an average of 3.2 years.
Summary of the benign FNAC diagnoses
In the indeterminate FNAC group, 19 of the 35 patients had surgical removal of their mass; 16 received nonoperative management. Of these, 25 were benign (70.6%), four were high-grade malignant (11.8%), three were low-grade malignant (8.8%), and three were nongraded malignant (8.8%).
In the malignant FNAC group of 129 patients, there were 59 high-grade sarcomas, three and nine of which were metastases and local recurrences. There were 14 low-grade primary sarcomas and four low-grade recurrent sarcomas (Table ). A subtype or cytomorphologic group and grade were rendered in 88 of 108 (81.5%) and 77 of 108 (71.3%) sarcomas, respectively.
Summary of malignant FNAC diagnoses
Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for all patients who had FNAC (including those with indeterminate reports). These values were reported for patients with histopathologic confirmation and patients with either histopathologic confirmation or clinical followup. The accuracy of grading and subtyping malignant lesions was calculated based on cases with a FNA diagnosis and histopathologic confirmation. The number of patients treated after FNA without additional biopsy and the number of nondiagnostic FNAs were reported as percentages of the total FNA cases.