The relationship between multiple intrathyroidal involvement in papillary thyroid carcinoma and chronic non-specific thyroiditis.

The relationship between multiple intrathyroidal involvement (MII) and chronic non-specific thyroiditis (CT) was investigated in 69 papillary thyroid carcinoma patients who received a subtotal or total thyroidectomy. The overall incidence of MII in patients with CT and the incidence of MII in the affected lobe of the patients with CT were significantly higher than that without CT (P = 0.0012 and 0.0425, respectively). Because Hashimoto's thyroiditis is believed not to carry the increased risk of associated thyroid malignancy, the high incidence of MII in the affected lobe in the case with CT is postulated to be caused by intraglandular metastases.