Comparison of ultrasound-guided core biopsy versus fine-needle aspiration biopsy in the evaluation of salivary gland lesions

Ultrasound-guided core biopsy provides many benefits compared with fine-needle aspiration cytology and has begun to emerge as part of the diagnostic work-up for a salivary gland lesion. Although the increased potential for tumor-seeding and capsule rupture has been extensively discussed, the safety of this procedure is widely accepted based on infrequent reports of tumor-seeding. In fact, a review of the literature shows only 2 cases of salivary tumor seeding following biopsy with larger-gauge needle characteristics, with 2 reported cases of salivary tumor seeding following fine-needle aspiration cytology. However, the follow-up interval of such studies (<7 years) is substantially less than the 20-year follow-up typically necessary to detect remote recurrence. Studies on tumor recurrence of pleomorphic adenoma, the most common salivary gland lesion, suggest that as many as 16% of tumor recurrences occur at least 10 years following initial surgery, with average time to recurrence ranging anywhere from 6.1 to 11.8 years postoperatively. Despite the benefits of ultrasound-guided core biopsy over fine-needle aspiration biopsy, which include both improved consistency and diagnostic accuracy, current studies lack adequate patient numbers and follow-up duration to confirm comparable safety profile to currently accepted fine-needle aspiration cytology. In this report we: (1) compare the relative benefits of each procedure, (2) review evidence regarding tumor seeding in each procedure, (3) discuss time course and patient numbers necessary to detect tumor recurrence, and (4) describe how these uncertainties should be factored into clinical considerations.