The biological activity of acinic cell carcinoma is uncertain. Histological dedifferentiation is one possible reason for recurrent disease, and this study was undertaken to assess its importance in acinic cell carcinoma. The initial and recurrent specimens from five patients with acinic cell carcinoma were assessed histologically and using flow cytometry, AgNOR estimation and morphometric analysis for evidence of dedifferentiation. No objective evidence of a change in biological aggressiveness in recurrent acinic cell carcinoma was identified. In this limited series of a rare salivary gland tumour, it would appear that factors other than dedifferentiation, such as close/involved margins, histological type and stage have a more meaningful effect on the likelihood of recurrence and prognosis.
