Fine needle aspiration cytology of paediatric soft tissue tumours highlighting challenges in diagnosis of benign lesions and unusual malignant tumours.

Abstract

The type of soft tissue lesions seen in children differs from that seen in adults. The role of fine needle aspiration (FNA) cytology in their diagnosis is not well documented. To study the cytopathological spectrum of paediatric soft tissue tumours to highlight uncommon benign and malignant lesions and the challenges in their diagnosis. A 3-year retrospective audit of all paediatric soft tissue FNA cytology cases from 2015 to 2017 was performed. Smears were reviewed along with cell block immunocytochemistry and follow-up histopathology of resected specimens wherever available. A total of 127 cases were reviewed, which included 72 benign and 55 malignant soft tissue tumours. Uncommon lesions described herein are myxoid fibrohistiocytic tumour, myxoma, lipoblastoma, Bednar tumour, malignant extra-renal rhabdoid tumour and desmoplastic small round cell tumour. Histopathology confirmation was available in 25 cases, out of which 16 cases were completely concordant. In eight cases, all benign diagnoses, histopathology provided more accurate subtyping than FNA. These included cases of lipoblastoma, myxoma and spindle cell haemangioma. FNA cytology of paediatric soft tissue tumours is accurate in classifying lesions as benign or malignant which helps in treatment planning. Immunocytochemistry performed on cell blocks is useful for subtyping malignant lesions.