Posters

Introduction  Fine needle aspiration (FNA) cytology of the thyroid is a well-established test in the clinical work-up of patients with solitary nodules of the thyroid. Thyroid FNA does however have limitations and audit of diagnostic performance is important.
Methods  The histopathology archives of the Royal Victoria Hospital were searched for all thyroid resections and the histopathological diagnosis was correlated with the pre-operative cytological diagnosis, where available. Special emphasis was placed on the accuracy of tumour diagnosis.
Results  A total of 173 cases were identified during the 2-year period, of these 93 had available pre-operative FNA. A total of 57 tumours were identified. A small number (six of 57) of significant discrepancies were identified. These included a malignant lymphoma diagnosed as Hashimoto's thyroiditis, a metastasis which the FNA had suggested was a medullary carcinoma and an insular carcinoma diagnosed as medullary carcinoma on FNA. False positives included a colloid cyst diagnosed as suspicious of malignancy and a cytological diagnosis of papillary carcinoma not confirmed on histology.
Discussion  At present, the majority of thyroid FNAs in our clinics are performed by surgeons and material is not routinely available for immunocytochemistry. In spite of these limitations, there were few major discrepancies. These might be reduced if pathologist aspirators were able to perform FNAs and collect material for further studies, where necessary. This would allow identification of medullary carcinomas and malignant lymphomas.
Conclusion  FNA of thyroid lesions is a useful investigation in our clinical setting, however, some areas of potential for improvement have been identified.