An Institutional Experience of Core Needle Biopsy with Cooperative Implementation by Pathologists and Head and Neck Oncologists in Salivary Gland Carcinoma.

Purpose: A major problem in establishing treatment strategies for salivary gland carcinomas is the difficulty of preoperative histologic subtyping. Core needle biopsy (CNB) allows the collection of a small, intact specimens from the tumor center for detailed analysis. We evaluated the efficacy and limitations of preoperative diagnosis with CNB specimens collected using a newly developed 20-gauge needle designed to popularize its use.

Methods: Paired preoperative CNB and surgical specimens from 41 patients with malignant salivary gland tumors were retrospectively reviewed. A histologic typing platform, including morphologic and immunohistochemical evaluation and fluorescence in situ hybridization, was evaluated using CNB specimens. Biopsy specimen quality, diagnostic accuracy, and immunohistochemistry concordance rates between biopsy and surgical specimens were analyzed.

Results: In 39 of the 41 patients, CNB provided high-quality specimens, enabling adequate morphologic, immunohistologic, and genomic analyses. In two patients, high-quality CNB specimens could not be obtained due to cystic fluid and tumor firmness. The overall accuracy of correct preoperative diagnosis was 75%. The success rate of histologic subtyping and HER2 immunostaining concordance between CNB and surgical specimens was lower in carcinoma ex-pleomorphic adenoma (CXPA) than in de novo carcinoma (histologic subtyping; CXPA vs de novo carcinoma 50% vs 89%, p = 0.016, HER2 concordance; salivary duct carcinoma [SDC] ex-PA vs de novo SDC 16% vs 100%, p = 4.66E-03). No recurrence occurred due to tumor seeding after CNB.

Conclusions: Highly accurate histologic subtyping of salivary gland carcinomas can be performed by preoperative CNB; however, specificity can be more challenging in pathologically heterogenous tumors.