CHRONIC THYROIDITIS AND DIFFERENTIATED THYROID CANCER: FROM OVERLAPPING HIGH PREVALENCE TO A SHIFT ON MULTIFOCAL INTRA-THYROID PAPILLARY THYROID CARCINOMA
Abstract
The autoimmune background as found in chronic thyroiditis (CT), also known as Hashimoto’s thyroiditis or autoimmune lymphocytic thyroiditis, does not represent an indication of surgery but the discovery of macro-nodules may represent a risk for thyroid cancer, thus thyroidectomy becomes an important tool of approach. Environmental triggers, less or more described up to this moment, are a contributor to higher prevalence of CT and to the shift through more frequent cases of papillary thyroid cancers (PTC) rather than follicular type. This is a mini-review of literature focused on the association between CT and differentiated thyroid cancer, especially PTC. The research used as key words all the mentioned synonyms used for CT. A number of 62 references are selected, since 2004 (while 45 of them are published between 2015 and 2017), and 53 of them are accessible via PubMed database. The CT - PTC relationship may be described at different levels: PTC is presented more frequently than follicular thyroid cancer in relationship with iodine supplements including cases with autoimmune background; 2. CT is involved in multifocal PTC but this histological pattern may not be more aggressive than generally expected because lymph nodes are somehow blocked by the immune process and protected by lymph nodes metastasis from primary thyroid source of PTC so the risk of recurrence and aggressive profile is not higher than seen in CT-free subjects. Team approach is essential for many aspects as the detection of CT and the selection of those rare cases that need thyroidectomy. The association between CT and PTC is actually more frequent that expected, especially for micro-PTC subtype. Overall, the survival of PTC patients does not seem to be influenced by CT if surgery is correctly applied despite a risk of multifocal intra- and not extra-thyroid spreading of malignancy.