Do black (Dark) lymph-node metastases in papillary thyroid carcinoma suggest more advanced or aggressive disease?

Background: In some patients, papillary thyroid carcinoma (PTC) lymph-node metastases are noted to be black (dark) in color at the time of surgical removal. The goal of this project was to determine histological, genetic, and clinical features that are associated with regional black PTC metastasis. Methods: Fifteen patients with black PTC metastases (black-PTC) were compared to a control cohort of 15 patients with nonblack PTC metastasis (nonblack PTC). Each sample was evaluated for the histological characteristics, BRAF V600E mutational status, and associated patient clinical data. Results: The degree of cystic degeneration (80% vs. 27%, p=0.004), percent hemosiderin deposition (20% vs. 6%, p=0.001), and presence of classical variant (100% vs. 67%, p=0.018) were significantly greater in black PTC than nonblack PTC (α=0.05). Other results were not significantly different. Conclusion: This study demonstrates that black compared to nonblack metastases have a greater degree of cystic degeneration and hemosiderin deposition leading to discoloration, and a trend toward an increased incidence in BRAF V600E mutations. This study is the first of its kind to describe the clinical, pathological, and genetic features associated with black PTC lymph-node metastasis.