Thyroid cancer in black thyroid glands: The effect of age and race

Background: Black thyroid pigmentation is a rare entity. The risk of malignancy is higher in black thyroid compared to non-black thyroid glands. We aimed to examine the effect of age and race on the risk of malignancy in black thyroid glands. Methods: We identified a series of consecutive patients who underwent thyroidectomy at an academic institution between January 1998 and May 2013. Patient demographics, clinical characteristics, and histopathology data were reviewed. Results: Among 925 patients who underwent thyroidectomy, 112 (12.1%) patients with black thyroid glands were identified. The incidence of thyroid cancer was 55.4% in black thyroid glands compared to 32.8% in non-black thyroid glands (p < 0.0001). The incidence of papillary thyroid cancer among the black and non-black thyroid glands was 34.8 and 20%, respectively (p < 0.001). The mean age (±SD) for patients with black thyroid glands and those with non-black thyroid was 54.3 ± 12.8 and 51.2 ± 15.7 years, respectively (p = 0.05). Black thyroid glands were also associated with a higher incidence of microcarcinomas (76 vs. 59%, p = 0.02). Among patients with black thyroid glands, Caucasians had a higher malignancy rate (63.4%) than African-Americans (37%; p = 0.03). Conclusion: The incidence of malignancy is higher in black thyroid compared to non-black thyroid glands, specifically in Caucasians.