Phyllodes tumour: cytologic and histologic presentation of 22 cases, and immunohistochemical demonstration of p53

A retrospective study of 22 cases of phyllodes tumour (PT) was undertaken to evaluate the potential value of fine needle aspiration (FNA) cytology in the diagnosis of benign and borderline PT. Histological material was available from 12 patients with typical benign PT (group 1), six patients with less typical changes (group 2) and four cases of borderline PT (group 3). Cytological presentation of PT in these cases was similar to that described by other cytologists, although abundant cellular material was obtained in only eight FNAs, naked nuclei were present in nine cases only, and atypical or suspicious cytological features were found in seven cases. Comparative analysis of p53 was made in nine patients with PT, five cases with other benign breast lesions and five with malignant lesions. p53 reaction was positive in five of nine patients with PT (all cases from groups 2 and 3), compared with two of five cases of carcinoma. p53 was negative in all patients with PT from group 1 and the five other benign cases. We suggest that cytopathologists should be careful when a myxoid stromal component is present in cytological smears.