Case 6 -

Mixed papillary, insular, and anaplastic carcinoma of the thyroid Dr. Ed Cibas

Clinical History 64 year old woman with a hard right thyroid mass. (FNA of thyroid, ThinPrep) Case 6 - Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Cytologic diagnosis: POSITIVE FOR MALIGNANT CELLS. Papillary carcinoma and anaplastic carcinoma. Thyroidectomy (2 weeks after FNA): CARCINOMA OF THE THYROID (4.5 cm) with multiple components: Papillary (10%) Insular (30%) Anaplastic, with squamous differentiation (60%) Diagnosis: Mixed papillary, insular, and anaplastic carcinoma of the thyroid Discussion: Anaplastic (undifferentiated) carcinoma is a highly malignant thyroid cancer that comprises less than 5% of thyroid carcinomas. Many cases are associated with a well and/or poorly differentiated carcinoma of the thyroid, as in this case. For this reason, it is believed that most (if not all) anaplastic carcinomas are the result of dedifferentiation of a pre-existing well or poorly differentiated carcinoma. Investigators from Ljubljana, Slovenia reported their FNA experience with 113 anaplastic carcinomas (Us-Krasovec et al, 1996). Of these, 10 (9%) showed an association with a differentiated carcinoma, as in this case. The proportion of anaplastic component in these mixed cases was variable. In some, the anaplastic component was represented by only a few anaplastic cells. We agree with the conclusions of those authors, namely, that the cytologist should be aware that mixed patterns occur, and be on the lookout for an undifferentiated (anaplastic) component. Not surprisingly, the insular component was not recognized as such in the FNA sample. The difficulty in rendering a specific diagnosis of insular carcinoma in an FNA sample has been well documented. Although characteristic features have been described, it has not yet been shown that they have improved the pre-operative recognition of insular carcinoma. Thinlayer preparations are an increasingly common alternative to conventional smears for thyroid FNAs. At the Brigham and Women's Hospital, we have been preparing 2 ThinPrep slides (instead of smears) on thyroid FNAs for almost 10 years, with excellent cyto-histo correlation. The advantages of thinlayer preparations over smears include reduced blood; ease in preparation of consistently well fixed slides, particularly when the FNA is not performed by a pathologist; and decreased screening time. Architectural features (macrofollicles and their fragments; microfollicles) are retained, but adjustment to mild alterations in cellular appearance is necessary (Frost, 1998; Biscotti, 1995; Tulecke, 2004). The accuracy in identifying neoplasms is similar for conventional smears and thinlayer slides (Frost, 1998; Biscotti, 1995). Recognizing chronic lymphocytic thyroiditis on thinlayer preparations requires experience because the lymphoid cells are intermingled with peripheral blood leukocytes (Frost, 1998). Two thinlayer slides are sufficient for diagnosis in most cases, but additional slides can be helpful in selected cases (Frost, 1998). References: Insular and anaplastic carcinoma of the thyroid Clark DP, Faquin WC. Thyroid Cytopathology. Springer, New York, 2005, pp. 80-82, 164-178. Guiter GE, Auger M, Ali SZ, Allen EA, Zakowski MF. Cytopathology of insular carcinoma of the thyroid. Cancer (Cancer Cytopathol) 1999; 87: 196-202. Nguyen G-K, Akin M-RM. Cytopathology of insular carcinoma of the thyroid. Diagn Cytopathol 2001; 25: 325-330. Ordonez N, Baloch Z, Matias-Guiu X et al. Undifferentiated (anaplastic) carcinoma. In: DeLellis RA, Lloyd RV, Heitz PU, Eng C. Pathology and Genetics of Tumours of Endocrine Organs. IARC Press, Lyon, 2004, pp. 77-80. Us-Krasovec M, Golouh R, Auersperg M, Besic, Ruparcic-Oblak. Anaplastic thyroid carcinoma in fine needle aspirates. Acta Cytol 1996; 40: 953-958. The ThinPrep for thyroid FNA Biscotti CV, Hollow JA, Toddy SM, Easly KA. ThinPrep versus conventional smear cytologic preparations in the analysis of thyroid fine-needle aspiration specimens. Am J Clin Pathol 1995; 104: 150-153. 2. Frost AR, Sidawy MK, Ferfelli M et al. Utility of thin-layer preparations in thyroid fine-needle aspiration: diagnostic accuracy, cytomorphology, and optimal sample preparation. Cancer (Cancer Cytopathol) 1998; 84: 17-25. 3. Malle D, Valeri R-M, Pazaitou-Panajiotou K et al. Use of thin-layer technique in thyroid fine needle aspiration. Acta Cytol 2006; 50: 23-27. 4. Tulecke MA, Wang HH. ThinPrep for cytologic evaluation of follicular thyroid lesions: correlation with histologic findings. Diagn Cytopathol 2004; 30: 7-13.