Ectopic bone formation and extramedullary hematopoiesis in the thyroid gland: report of a case and literature review.

This purpose of this article is to document ectopic bone formation (EBF) and extramedullary hematopoiesis (EMH) in thyroidectomy specimens. We present a case of multinodular goiter with EMH and EBF, as well as a literature review of studies published in the English language on EMH and/or bone formation in the thyroid gland, accessed through PubMed and Google Scholar databases. Thirteen published cases of EMH and/or EBF in the thyroid gland were evaluated, and a case of multinodular goiter with histopathologically proven EMH and EBF in a 54-year-old woman is herein presented. In the reviewed literature, 12 patients were women, and 1 was a man (age range, 28-82 years; median, 56.46 +/- 18 years). EMH was histopathologically detected in 8 patients, EMH and EBF were detected in 4 patients, and only bone formation was detected in 1 patient. Although a solitary nodule was detected in 7 patients, multinodular goiter was detected in 6 patients. Fine needle aspiration cytology was used in the preoperative period to arrive at a diagnosis in 6 of the 13 patients, but it was not possible to obtain proper biopsy material in the remaining patients. Although no previously known hematologic disease was detected in 11 patients, 2 were known to have myelofibrosis in the preoperative period. When EMH is pathologically detected in the thyroid, the question of whether there is an underlying hematologic disease in the patient must be investigated. In addition, it must be kept in mind during fine needle aspiration cytology and frozen section examinations that EMH maybe among the differential diagnoses for anaplastic thyroid cancers.