Analysis of Malignant Thyroid Neoplasms with a Striking Rise of Papillary Microcarcinoma in an Endemic Goiter Region

According to National Cancer Registry Program, Thiruvananthapuram district of Kerala, has the highest relative frequency of thyroid carcinomas; nevertheless, limited data exist regarding its socio-demographic and clinico-pathological characteristics. The aims of the study were to assess the: (1) demographic characteristics, (2) histopathological features and the relative frequency of various thyroid carcinoma cases and papillary thyroid carcinoma (PTC) subtypes, (3) rising trend of papillary microcarcinomas, and (4) associated lesions. A retrospective study wherein 170 cases of thyroid malignancies reported in our single institution over a period of 8 years period was reviewed. PTC accounted for 97% cases, followed by medullary (n = 4; 2.4%) and follicular carcinoma (n = 1; 0.6%). There was female preponderance (p = 0.0379) with a lower median age in females (p = 0.0275). Among the PTCs, conventional type constituted 53.4% cases (n = 87), followed by microcarcinomas (n = 34; 20.9%), follicular variant (n = 28; 17.2%), and others 14 cases (8.5%). Thirty-three cases (19.4%) showed multifocality, 5 cases (2.9%) extra-thyroid extension, and 19 cases (11.2%) lymph node metastasis. Two cases developed recurrences and three cases, metastasis. The associated lesions were significantly higher in females (p = 0.0059); most common being multinodular goiter (MNG; n = 67; 41.1%), followed by Hashimoto thyroiditis (n = 44; 27%) and lymphocytic thyroiditis (n = 28; 17.2%); MNG being associated with follicular (p = 0.0129), and Hashimoto thyroiditis with conventional variant (p = 0.0475). The frequency of microcarcinomas significantly increased in the past 4 years (p = 0.0291) and was associated with MNG (p = 0.0055), Hurthle cell nodule (p = 0.0315) and absent lymph node metastasis (p = 0.0147). The primary treatment modality was total thyroidectomy. Papillary microcarcinoma cases increased significantly in the past 4 years and were significantly associated with MNG and Hurthle cell nodule. It is challenging to distinguish the various PTC subtypes as recognition of these histological variants warrants better patient management.