HASHIMOTO
THYROIDITIS AND THYROID CANCER
For many
years, there have been questions regarding the association between the thyroid
inflammation seen in Hashimoto thyroiditis (HT) and thyroid cancer. The results
of previous studies have been inconclusive.
In a recent
prospective study, which included a very large cohort of adult patients (n=9.851)
with thyroid nodules > 1 cm, the authors found that in patients with thyroid
nodules, HT is associated with a higher rate of indeterminate cytology than in
the non-HT patients (26 % vs 22 %, p< 0.01). This is not surprising, since
the inflammation typically associated with HT can cause reactive atypia in the
thyroid follicular cells. This reactive atypia mimics the findings in papillary
thyroid cancer (such as increased nuclear size and nuclear contour irregularities
and grooves), resulting in an indeterminate diagnosis for FNA samples. An
increase in malignant cytology was also identified in HT patients. Cancer
within the thyroid nodule(s) was diagnosed on
histopathology more frequently in the HT patients as compared to the
non-HT patients (for solitary nodules: 24.5 % vs. 16 % [p<0.01], for
multiple nodules: 22 % vs 15 % [p<0.01]). There were no significant
differences in pathologic characteristics or markers of biological
aggressiveness between the two groups. This indicates that the inflammatory
effect does not affect the biological behavior of the cancer.
These findings
have clinical significance, as both HT and thyroid nodules are so common.
Thyroid ultrasonography is mandatory in all patients with HT to evaluate for
the presence of thyroid nodules and define their ultrasonographic features. Sonographic features of thyroid cancer are similar in patients with and
without Hashimoto thyroiditis. Among patients
with Hashimoto thyroiditis and thyroid cancer, the sonographic appearance of the
cancerous nodule is similar, except that cancerous nodule margins are more
likely to be irregular or poorly defined when the gland is heterogeneous.
Of note, 9 cases
of thyroid lymphoma were identified among the patients with HT.
Σχόλια
Δημοσίευση σχολίου