Poorly-differentiated adenoid cystic carcinoma: cytologic appearance in fine-needle aspirates of distant metastases.

Adenoid cystic carcinoma (ACC) is a primary salivary-gland neoplasm which typically yields characteristic cytomorphology upon fine-needle aspiration (FNA). We report on the FNA findings of a case of ACC metastatic to the liver which demonstrated a predominantly solid, poorly-differentiated pattern, an unusual but well-recognized subtype associated with a poor clinical outcome. The FNA findings in 7 additional cases of ACC metastatic to distant sites were also reviewed, with 4 cases displaying a prominent poorly-differentiated component. These findings suggest that, although not commonly recognized in salivary-gland FNAs, the poorly-differentiated pattern of ACC does occur in metastatic deposits and should be recognized as such, thereby preventing a needless search for a second primary malignancy.