Extramedullary Hemopoiesis in a Thyroid Nodule with Extensive Bone Metaplasia and Mature Bone Formation

Abstract

Thyroid nodules may undergo a wide range of degenerative change such as infarction, hemorrhage, or fibrosis, which may be localized or extensive and associated with calcification or even ossification. However, the detection of true bone formation in a thyroid nodule is a very rare occurrence. Extramedullary hemopoiesis (EMH) has been described in almost every organ of the body, mainly in tissues active in hemopoiesis in embryonic life. It is extremely rare for EMH to occur in the thyroid gland especially in patients without known chronic anemia. We describe a case of a cold thyroid nodule with histologically proven extensive bone metaplasia and formation of mature bone with foci of hemopoietic tissue in a young woman without chronic anemia, which, to the best of our knowledge, is the first to be reported in the English language literature.

Intrathyroidal hematopoiesis: a rare histological finding in an otherwise healthy patient and review of the literature

“…One patient presented with a hard lesion of 7 cm diameter that necessitated decalcification before gross sectioning [10]. With the second patient, a 3-cm nodule was found in one lobe with a central area of calcification [6], similar to our case.…”

“…With the second patient, a 3-cm nodule was found in one lobe with a central area of calcification [6], similar to our case. In all three cases, the intertrabecular spaces displayed mature fat cells together with hematopoietic elements of megakaryo-and myelopoiesis [10], "scattered foci of hematopoietic tissue" [6], while particularly erythroid precursors were found in our case.…”

“…An extensive database research yielded two previous reports on bone formation with hematopoietic elements [6,10], whereas EMH was found in seven cases [8,9,[11][12][13]15]. However, in one case report the finding of hematopoietic cells was interpreted as contamination [15].…”

Osseous metaplasia with mature bone formation of the thyroid gland: Three case reports

“…Occasionally, osseous metaplasia is observed (1). Although dystrophic calcification may often be detected in a nodular goiter, maturation of this calcified tissue to mature bone is extremely rare (12). …”

Bone formation within a breast abscess

“…This process is described as metaplasia. Osseous metaplasia can be defined as the presence of heterotrophic bony tissue within a soft tissue and can be clinically difficult to distinguish from carcinoma1 2 It has been noted to follow soft-tissue tumours, trauma and post-traumatic haematoma 2. However it has not been known to be present within a poorly healing breast abscess.…”