engleski

INTRAOPERATIVE ANALYSIS OF THYROID LESIONS: A SINGLE INSTITUTION EXPERIENCE

INTRODUCTION: Frozen section analysis had a great value in the operative management of thyroid lesions in the past. However, with the widespread use of fine needle aspiration biopsy (FNA), the value of frozen sections has been questioned. Although FNA is cost-effective and easy to perform, frozen sections are still preferred by some institutions. METHODS: All patients with thyroid disease operated on between January 2000 and December 2004 at University Hospital for Tumors were identified. Data obtained from pathology files included patient age and sex, number of frozen sections performed, frozen section results, and final histologic diagnosis. RESULTS: A total of 887 patients, 781 (88%) women and 106 (12%) men, were identified. Median age for women was 50 (range 8-80) and for men 52 (range 15-85) years. Frozen section was performed in 675 (76%) patients. The number of examined frozen sections varied from one in cases of macroscopically benign conditions such as nodular goiter to four when malignant follicular lesion was suspected. The intraoperative diagnosis was benign in 135 (20%) and malignant in 172 (25.5%) patients. In 368 (54.5%) patients frozen section showed follicular neoplasm and definitive diagnosis was postponed until final sections. Intraoperative analysis properly recognized 157 (95%) of 165 papillary carcinomas, 3 (14%) of 21 follicular carcinomas, all 7 cases of medullary carcinoma, and two anaplastic carcinomas. In 3 patients with the diagnosis of malignant tumor, final histologic sections revealed a collision tumor (medullary and follicular carcinoma), insular carcinoma and one squamous carcinoma. In 3 cases papillary carcinoma was misinterpreted as follicular lesion, and another five carcinomas, smaller than 5 mm, were found close to serial sliced follicular encapsulated lesions. DISCUSSION: During the last two decades the benefit of intraoperative frozen section analysis in thyroid surgery has been questioned by many authors. Commonly mentioned disadvantages include a limited number of performed sections, lower quality of intraoperative slides, artifact nuclear clearing, difficult interpretation of post-FNA changes, and identification of vascular/capsular invasion. Our study showed a high sensitivity of frozen sections in the diagnosis of papillary lesions. False-positive results of pseudopapillary hyperplasia in hyperplastic nodules misinterpreted as carcinoma were minimized with the experience of the performing pathologist. Intraoperative diagnosis can be difficult in cases of follicular variant of papillary carcinoma or microcarcinoma which can be incidentally found during evaluation of another thyroid lesion (as was the case in 3 and 5 of our patients). The value of frozen sections in the diagnosis of follicular lesions remains uncertain. Our series showed that only 3 of follicular carcinomas with macroscopically suspect invasion were properly recognized with the use of multiple frozen sections. Therefore, an agreement was reached between the surgeon and the pathologist that all follicular and oncocytic lesions except for those clearly malignant on intraoperative sections should be defined as “follicular” or “oncocytic” tumor, and definitive diagnosis postponed until examination of serial sections. Frozen sections can be used for accurate identification of intrathyroid parathyroid neoplasms, normal parathyroid glands, and lymph nodes that may contain metastatic thyroid carcinoma. Although easy to diagnose, the use of frozen sections in the evaluation of non-neoplastic conditions such as nodular goiter and thyroiditis is not justified, except in cases when neoplasm is suspected on preoperative FNA. CONCLUSION: Intraoperative frozen section analysis has a great value in the diagnosis of papillary lesions and nodal involvement of thyroid primaries, especially in cases when preoperative FNA was inconclusive or suspicious for malignancy. Frozen sections are of limited value in the diagnosis of follicular and oncocytic tumors and papillary microcarcinoma. With the wider use of FNA and growing experience of cytopathologists, non-neoplastic thyroid diseases as well as clearly malignant neoplasms can be accurately diagnosed preoperatively and definitive surgical treatment can be planned according to FNA results. However, in most institutions final decision which method to use depends on the surgeon’s experience and quality of cooperation with the performing pathologist and cytopathologist.

frozen tissue; thyroid;

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