Is Hashimoto's thyroiditis a prognostic factor for thyroid papillary microcarcinoma?

The relationship between papillary thyroid carcinoma (PTC) and accompanying Hashimoto's thyroiditis (HT) has been investigated extensively. However, there is no agreement among the authors. We aimed with this study to investigate this relationship in a limited subtype of PTC called papillary thyroid microcarcinoma (PTMC).

Between January 1999 and December 2012, 1923 thyroids were surgically resected in two referral centers and thoroughly inspected for evidence of PTMC. Of these patients, 172 who were diagnosed with PTMC had demographic and pathological features recorded.

Fourteen patients (8.1%) were found to have CLN metastases. Eleven (78.6%) of the patients with CLN metastases had tumors larger than 5 mm, and 3 (21.4%) patients with CLN metastases had small tumors (≤ 5 mm), but there was no statistical significance (p > 0.05). Accompanying Hashimoto's thyroiditis (HT) was detected in 67 (39%) patients. The CLN metastasis rate was slightly higher in cases with HT in surrounding thyroid tissue. However, there was no statistical significance; the CLN rate was 6.7% (n=7) in patients without thyroiditis and 10.4% (n=7) with Hashimoto's thyroiditis. Insufficient FNA results in patients with thyroiditis were associated with HT (p < 0.05).

Surgeons and other clinicians who play a role in the treatment of thyroid cancers should be aware that some PTMC cases may show a worse course, as with some PTCs, contrary to expectations.