Clinical Significance of Fine-needle Aspiration Biopsy in Major Salivary Gland Tumors

We compared preoperative evaluations of 93 fine-needle aspiration biopsies (FNAB) of major salivary gland tumors done over a 5 year period with pathologic diagnoses of surgically resected specimens. The overall accuracy was 88.5%. Eight of 15 aspirates from malignant tumors were correctly diagnosed by FNAB, for a sensitivity of 53.3%, while 69 of 72 aspirates from benign tumors were correctly diagnosed by FNAB, for a specificity of 95.8%. Five malignant tumors diag- nosed as benign by FNAB were squamous cell carcinoma, carcinoma in pleiomorphic adenoma, malignant lymphoma, low-grade mucoepidermoid carcinoma, and acinic cell carcinoma. The false negatives in the first 2 cases appeared to be due to inaccurate placement of the aspiration site. The other 3 cases showed lack of atypia, leading to a benign diagnosis. Malignant lymphoma is difficult to diagnose as malignant, even in properly aspirated specimens, so we recommend open biopsy when malignant lymphoma is suspected from physical and radiological examinations. A case confirmed pathologically as benign myoepithelioma was diagnosed as adenoid cystic carcinoma preoperatively, based on the finding of a cribriform pattern containing mucin. It should be borne in mind that myoepithelioma and adenoid cystic carcinoma are difficult to distinguish by FNAB.Although FNAB is useful in diagnosing major salivary gland tumors, its low sensitivity (high percentage of false negatives) is undesirable. It may thus be helpful in intraoperative decision-making when combined with frozen sectioning.