Assessment of a cytology grading system for head and neck masses

A grading system for Fine Needle Aspiration Biopsy Cytology (FNAC) has been in routine use in Peterborough since 1994 for reporting on fine needle aspiration biopsies of neck lumps. The records of all 276 patients who had neck lump fine needle aspiration biopsies performed between 1994 and 1999 were reviewed retrospectively. The 193 patients who had definitive histology available were included in the study of whom 154 (80.2%) were considered adequate for grading. A learning curve for adequacy of specimens obtained is demonstrated, with adequacy rate increasing with increasing experience or seniority of the sampler. The grading system produced an overall accuracy rate of 73.3% with a predictive value for malignancy of 88.6% and a predictive value for benign conditions of 67.3%. Individual grades were assessed for predictive value of benign or malignant disease. Grade 5 proved completely reliable, with a predictive value for malignancy of 100%. The shortcomings of the other grades and the difficulties in diagnosing lymphoma by FNAC are discussed.