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

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.

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.

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).

The incidence of malignancy is higher in black thyroid compared to non-black thyroid glands, specifically in Caucasians.