Acinic cell carcinoma of the parotid gland

Abstract

In a histological re-examination and re-classification of a series of 1,678 tumors of the parotid gland 37 (2.2%) exhibited the structures characteristic of acinic cell carcinoma. A long-term follow-up study showed that the prognosis quoad vitam in this type of tumor is poorer than previously has been inferred from short-term follow-ups. Thus the determinate survival rate fell from 89% at 5-year follow-up to 56% after 20-year follow-up. The prognosis is nevertheless much better than in adenoid cystic carcinoma of the parotid gland, as disclosed by a comparative study. This difference is evident after 5-year follow-up and becomes still more marked with time. Acinic cell carcinoma cannot be divided into a benign and a malignant variant on the basis of various histological criteria, such as infiltrative growth and high incidence of mitesis. This is because even the histologically apparently benign variant may have a clinically malignant course. Metastasis was observed in 7 cases, in 4 of them to regional lymph nodes. Since acinic cell carcinoma has proved to be a malignant, metastatic type of tumor, the authors recommend that parotidectomy be combined with neck dissection.