Utility of cytomorphologic criteria and p53 immunolocalization in distinguishing benign from malignant cystic squamous-lined lesions of the neck on fine-needle aspiration.

Fine-needle aspiration can effectively distinguish between benign and malignant cystic lesions of the head and neck. However, in some instances it may be difficult to arrive at a definite diagnosis due to limited cellularity, reactive changes, and cellular degeneration. In this study we examined the usefulness of six cytomorphologic features including the presence or prevalence of nuclear atypia, anucleated cells, tissue fragments, necrosis, and background inflammation in distinguishing between benign and malignant cystic lesions of the head and neck. The case cohort comprised 14 benign and 22 malignant cases. P53 immunostain was performed in 19 cases. These features were semiquantitatively measured on a sliding scale of 0-4 in both air-dried Diff-Quik-stained, alcohol-fixed Papanicolaou-stained smears and Millipore filter preparations. Mean and standard errors were calculated and statistical significance was evaluated by unpaired t-test (StatView). Increased number of tissue fragments (P < 0.001), greater degree of nuclear atypia (P < 0.001), and background necrosis (P < 0.001) were more frequent in cystically degenerating squamous carcinoma as compared to benign squamous cystic lesions. No significant differences were noted in the number of single cells, anucleated cells, or in the amount of background inflammation found in aspirates of benign vs. malignant cystic squamous lesions. A higher percentage of the malignant cystic squamous lesions FNA cases demonstrated p53 immunolocalization but this difference was not statistically significant. Application of the above-mentioned cytomorphologic criteria and the use of p53 immunostain could effectively distinguish between benign and malignant cystic lesions of the head and neck.