Fine-needle aspiration cytology of sarcoma: Retrospective review of diagnostic utility and specificity

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Abstract
Fine-needle aspiration cytology (FNA) is useful because of its low cost, quick turn around time, and low incidence of complications. This study investigates the role FNA plays in the evaluation of sarcoma. We reviewed all the pathologic material from patients with sarcoma or a FNA diagnosis suggestive of sarcoma at the University of California-Davis Medical Center (1985-1994). Fifty-two of 196 patients identified (26.5%) were evaluated with FNA exhibiting 46 soft tissue and 6 bone lesions located in the extremities (19), trunk (19), head and neck (8), retroperitoneum (3), and abdominal cavity (3). Among 196 patients identified, those evaluated by FNA had soft tissue rather than bone lesions (P < .001) and primary sites other than in the extremities (P < .001). The primary neoplasms for the 52 FNA patients included 47 sarcomas (10 malignant fibrous histiocytomas and 16 other types), 1 intramuscular myxoma, 2 lymphomas, and 2 spindle cell (sarcomatoid) carcinomas. In 43 patients (22% of total), FNA was used first, before a primary diagnosis. The FNA report showed the correct specific neoplasm in only 20.9%. However, the FNA reports reflected an effective positive diagnosis leading to appropriate diagnostic biopsy in 88.4%, while only 7.0% were misleading (benign or inflammatory) and 4.6% inadequate. Review of FNA slides for 32 of 43 patients in which FNA was used first, in a blinded fashion, exhibited 21.9% specificity for the specific neoplasm, and 88.4% effective positive diagnoses. In 9 patients, FNA was utilized to investigate recurrence. Five out of 5 instances of recurrent sarcoma were identified by FNA. However, FNA misidentified recurrence in 3/4 instances, exhibiting suspicious cells from regenerating skeletal muscle (2) and a traumatic neuroma (1). The specific diagnosis for sarcomas is challenging even with surgical material. FNA usually does not provide a specific diagnosis (only in 20.9% of cases) and review of routinely prepared slides showed the same specificity as reflected by the original FNA report, at times formulated with the benefit of immunohistochemistry or electron microscopy. FNA effectively evaluated lesions in 45 of 52 patients (86.5%), confirming the useful screening role for this technique in sarcomas.