High Malignancy Risk and Its Predictors in South Indian Patients With Bethesda II Thyroid Nodules.

Background: Global data reports a low malignancy risk, whereas regional data report a variable risk of malignancy in Bethesda II thyroid nodules. The limited availability of surgical histopathology might have underestimated the risk of malignancy. Here, we report the prevalence of malignancy and its predictors in Bethesda II thyroid nodules for which the surgical histopathological diagnosis was available.

Methods:  This retrospective study was done at a tertiary healthcare center in South India between January 2008 and September 2015. Case records of adults with thyroid nodules who underwent surgery were collected. Patients with inadequate data were excluded from the study. The data was analyzed using SPSS version 21.0 and a p-value of < 0.05 was considered statistically significant.

Results:  A total of 563 patients were included in the study with a mean age of 36±12 years. Serum thyrotropin (TSH) was low in 87 (15.4%) patients whereas 362 (64.2%) patients had multinodular goiter (MNG). Sonographic evidence of suspicious cervical lymph node and microcalcification was seen in four (0.7%) and 48 (8.5%) patients, respectively. A total of 48 (8.5%) patients had thyroid carcinoma in the final histopathology. Of these, 42 (87.5%) had papillary thyroid carcinoma, five (10.4%) had follicular thyroid carcinoma and one (4.1%) had anaplastic carcinoma. Age, gender, and maximum nodule size were not associated with malignancy. Thyrotoxicosis was negatively associated with malignancy whereas multi-nodularity, thyroid calcification, or suspicious cervical lymph node on ultrasound and total thyroidectomy were positively associated with malignancy on univariate analysis. On binary logistic regression, only the former four, but not total thyroidectomy, were independent predictors of malignancy.

Conclusions:  We report a high (8.5%) prevalence of malignancy among South Indian patients with Bethesda II thyroid nodules. Thyroid microcalcification, presence of suspicious cervical lymph node on ultrasound, and multinodularity were associated with high and suppressed TSH with low risk of malignancy. Further prospective studies are warranted to confirm the study observations.