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

Abstract

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.

Keywords: Associated lesions; Microcarcinoma; Papillary thyroid carcinoma; Thyroid malignancies; Variants.

Fig. 1

Photomicrographs showing a papillary carcinoma, conventional type (×10), b capsular and vascular invasion of follicular carcinoma (×10), c medullary carcinoma (Congo red stain and apple green birefringence in top and bottom inset respectively; ×10), (D) lymphoepithelial lesions in high grade non-Hodgkin lymphoma (×40)

Fig. 2

Cut section of thyroid showing papillary carcinoma, follicular variant

Fig. 3

Photomicrographs showing low power magnification of a microcarcinoma, b Hurthle cell variant, c Warthin-like, d columnar cell variant metastasis to lymph node, e follicular variant, f encapsulated variant, and g tall cell variant

Fig. 4

Year-wise distribution of microcarcinoma and papillary carcinoma