Fine needle aspiration cytology in two cases of well-differentiated acinic-cell carcinoma of the parotid gland. Discussion of diagnostic criteria.

Two cases of well-differentiated acinic-cell carcinoma of the parotid gland with diverse histology (one compact variant and one rare tubular-acinic type with an important lymphoid component) underwent fine needle aspiration. Both were clinically thought to be benign neoplasms but were correctly diagnosed preoperatively by aspiration cytology. Cytohistologic correlation in these cases showed that the decisive diagnostic criteria for well-differentiated acinic-cell carcinoma were the presence of atypical acinous structures and of cytoplasmic granules that were acid alcian blue negative and period acid-Schiff positive after diastase digestion.