Encapsulated follicular variant papillary thyroid carcinoma: problems in histological diagnosis

Thyroid neoplasms are the commonest endocrine neoplasms and account for the most number of thyroidectomies done. Encapsulated thyroid lesions are being encountered more commonly in thyroidectomy specimens in recent time. The present study was undertaken to analyse the incidence of thyroid malignancies with a changing pattern and to discuss the difficulties encountered in histopathological interpretation of encapsulated neoplastic lesions of follicular cell origin. It is a retrospective study done in the department of pathology, NRS Medical College, Kolkata. Data of all the thyroidectomy specimens examined over last four years (August 2006 to July 2010) were retrieved and slides were reviewed. All slides of thyroid lesion received in the department of pathology, NRS Medical College for review were also included in this study. Frequency distribution study was done with the sample analysed. Follicular variant of papillary carcinoma was the commonest type of thyroid malignancy, on review, with the encapsulated sub-variant exceeding the diffuse type. This variant is a diagnostic challenge because it has to be differentiated from other encapsulated follicular thyroid lesions, especially follicular adenoma. The data analysis, results and problems in the diagnostic protocols are discussed in this study along with review of literature. Reclassification of thyroid tumour may be warranted in future with this background.