Fine needle aspiration cytology of soft tissue tumours, its accuracy and pitfalls--our institutional experience

Abstract

Background: Soft tissue tumours are extremely rare neoplasms. Fine needle aspiration cytology (FNAC) is being increasingly used for diagnosing soft tissue tumours inspite of its poor sensitivity, specificity and inadequacy. Aims: The aim of this study is to study the usefulness of fnac in diagnosing and sub grouping of soft tissue lesions. Methods and Material: FNAC smears of 92 cases of soft tissue lesions with adequate cellularity (at least 5 clusters of 10 unobscured cells) were reported under the following cytomorphological headings- spindle cell, round cell, pleomorphic, myxoid and lipomatous type, along with benignicity or malignant nature of the lesion. Immunocytochemistry (ICC) was performed wherever feasible. Results: Out of the 92 cases, 61(66.3%) were benign, 21 (22.8%) malignant and 10 (10.9%) inconclusive on fnac. Benign lesions occurred in 2nd to 4th decade of life with a predilection for extremities (54%), whereas malignant tumours occurred in all age groups and at all sites. Males had a higher incidence than females. 87 %( 53 cases) of benign soft tissue lesions and 62 %( 13 cases) of malignant soft tissue lesions could be diagnosed by fnac alone, while ICC helped in 6 cases(out of 15). Lipomatous tumours (46%) were most easy to diagnose, whereas round cells, spindle cells and myxoid lesions were most difficult. False positive diagnosis was made in only 1% of adequate smears. Conclusion- In spite of its limitations, FNAC can be an useful cost-effective tool for preoperative diagnosis of soft tissue lesions, with low morbidity, high compliance and acceptable accuracy. Ancillary techniques like ICC can help in improving the accuracy of fnac diagnosis.