Ectopic Bone Formation in Thyroid Gland: Report of Sixteen Cases and Comprehensive Literature Review.

OBJECTIVE:This study aimed to analyze the outcomes of patients with ectopic bone formation (EBF) diagnosed in thyroidectomy specimen.PATIENTS AND METHODS:We retrospectively analyzed the data of 16 patients who underwent thyroidectomy between February 2009 and June 2018 and whose pathology examination diagnosed EBF.RESULTS:Fourteen patients underwent bilateral total thyroidectomy (BTT), one patient required BTT with central lymph node dissection, and one patient was subjected to BTT with functional lymph node dissection. On histopathological examination, left lobe EBF was diagnosed in four patients; left lobe EBF with bilateral papillary thyroid carcinoma (PTC) in two; left lobe EBF with left lobe PTC in one; left lobe EBF with left follicular adenoma in one; left lobe EBF with right lobe papillary thyroid microcarcinoma in one; bilateral EBF in one; right lobe EBF with extramedullary hematopoiesis in one; right lobe EBF in three; right lobe EBF with right lobe medullary thyroid carcinoma in one, and right lobe EBF with bilateral lymphocytic thyroiditis in one. One of the five patients who underwent bone marrow biopsy was diagnosed with myeloproliferative dysplasia, and another with polycythemia vera. Three patients were treated medically for anemia because no other pathological findings could be observed.CONCLUSIONS:There is a lack of literature data about the clinical significance of EBF in the thyroid gland in cases with no concomitant hematological diseases. People who have been diagnosed with EBF in the thyroid gland should be checked for hematological diseases.