Fine needle aspiration diagnosis of spindle cell tumors of soft tissue, including the use of ancillary methods, and correlation with clinical data

Abstract: Fine needle aspiration cytology (FNAC) is gaining increased popularity in the diagnosis of soft tissue lesions. FNAC used as a primary examination method to obtain a morphologic diagnosis, has been part of the diagnostic work-up of patients admitted to the Musculoskeletal Tumor Center of the Lund University Hospital since 1972. Accuracy of FNAC in distinguishing benign from malignant soft tissue tumors has been comparable to that of surgical biopsies, while its accuracy in establishing a specific subtype diagnosis has been inferior to surgical biopsies. The cytological examination of spindle cell tumors of soft tissue, which often share morphological and clinical characteristics, is a challenge. In addition, the literature on FNAC of spindle cell tumors is still sparse. The purpose of this study was both to describe the spectrum of FNAC findings in spindle cell tumors of soft tissue and also to analyze which ancillary methods can optimize FNA cytodiagnosis among these tumors in order to minimize the need for open biopsy. To this end, 238 FNA aspirates performed on 236 patients with five selected types of spindle cell tumors of soft tissue were analysed. In addition, clinical information and ancillary studies, which could increase the precision of cytodiagnosis were evaluated. The results of the study indicate the following: Different treatment options for some low grade and local aggressive/benign spindle cell tumors require an exact histotype diagnosis. This can be usually obtained from aspiration smears complemented by clinical data in elastofibroma dorsi and spindle cell lipoma due to their characteristic cytomorphology. FNAC evaluation of neurilemoma (schwannoma), leiomyosarcoma and dermatofibrosarcoma protuberans, requires the use of strict cytological criteria together with proper clinical information and often ancillary techniques. Correct cytologic diagnosis of spindle cell tumors is facilitated when fine needle aspiration cytology is used in the context of the clinical findings and when the cytological diagnosis is based on strict cytological criteria as well as ancillary techniques.