Ear, Nose & Throat Journal2023, Vol. 102(2) 126–129© The Author(s) 2022Article reuse guidelines:sagepub.com/journals-permissionsDOI: 10.1177/01455613221125922journals.sagepub.com/home/ear
Thyroid nodules are frequently accompanied by degenerative changes, such as hemorrhage, cholesterol crystallization, fibrous tissue deposition, or filling with fat. Although calcification is also a common phenomenon, osteogenesis, characterized by mature bone formation, is very rare. Here, we describe a case of Hashimoto’s thyroiditis with osseous metaplasia and ectopic bone formation case and discuss its possible causes.
Keywords
Hashimoto’s thyroiditis, osseous metaplasia, ectopic bone formation
Thyroid nodules are often accompanied by degenerative changes, such as hemorrhage, cholesterol crystals, fibrous tissue deposits, fat filling, or calcification. However, osseous metaplasia (OM) characterized by mature bone formation is very rare. Here, we report a case of Hashimoto’s thyroiditis (HT) with a cold thyroid nodule that was pathologically found to have OM and mature bone formation. we also summarize the case reports on osseous metaplasia, medullary metaplasia, ectopic bone formation and extramedullary hematopoiesis in thyroid hyperplasia, follicular adenoma, multinodular goiter, papillary thyroid carcinoma, and anaplastic thyroid carcinoma (Table 1).
A 63-year-old female patient was admitted to our hospital due to weight loss, polyphagia and hunger, fear of heat, and hyperhidrosis for 1 year. The patient has lost about 10 kg in weight within 1 year, without fever, dry eyes, eye pain, blurred vision, and hand and foot tremors. She had a medical history of asthma and COPD. Her physical examination was unremarkable except for a palpable thyroid nodule, movable on swallowing and without tenderness to palpation. Laboratory examinations revealed no significant abnormalities except for depressed TSH (0.049mIU/L).
Thyroid ultrasound showed a 1.5 × 2.0 cm sized hypoechoic nodule (C-TIRADS 4A) in the middle portion of the left thyroid lobe, regular in shape, clear boundary, and a large number of tufted calcifications were observed in its periphery. CDFI showed that there are not abundant blood flow signals in the nodules. Multiple enlarged hypoechoic lymph nodes were imaged in the bilateral neck’s I, II, and III regions. Thyroid gland scintigraphy with 99mTc showed a cold nodule with multiple calcifications in the left lobe of the thyroid gland. Twice fine-needle aspirations (FNA) were performed on this cold nodule, and cytology revealed papillary thyroid carcinoma (PTC).
The patients had a preoperative diagnosis of papillary thyroid cancer and subsequently underwent thyroidectomy. During the surgical procedure, it was found that a firm, 1.5 × 2.0 cm mass at the left middle pole of the thyroid gland, which boundary is clear and didn’t invade the surrounding tissue. The frozen section of the left thyroid lobe mass showed obvious calcification of the thyroid, severe cell extrusion, active proliferation, and abundant lymphoid tissue. Surgery continues with the removal of the remaining thyroid tissue and dissection of the central and left cervical lymph nodes. After the operation, the wounds healed at the first level, and the patient had no hoarseness or numbness of the limbs.
The postoperative pathological results were1 The left lobe showed Hashimoto’s thyroiditis with atypical adenomatous hyperplasia (focal papillary hyperplasia, tending to papillary thyroid microcarcinoma) and obvious calcification and ossification (bone marrow formation in the ossified area) ( Figure 1A-C). Immunohistochemical analysis revealed CK-H (+), TTF-1 (Weak+), CK19 (+), Galectin-3 (+, partial), TG (+), Ki-67 (+, <1%), and CD31 (+, vessel).2 The right lobe and pyramidal lobe showed HT with partial follicular dysplasia (Figure 1D and E).3 Lymph node biopsy showed reactive hyperplasia.
Thyroid nodules are common and most are benign. Palpable thyroid lesions account for 4–5% of the asymptomatic nodule. Ultrasound and autopsy studies have shown a prevalence of thyroid nodules as 50–67% in population. Ultrasound is the primary means of the initial evaluation of nodules and should be performed when a thyroid nodule is suspected. Conventional ultrasound enables a good comparison of benign and malignant thyroid nodules, which has a certain value in the differential diagnosis of benign and malignant thyroid nodules.8 Ultrasound–guided fine-needle aspiration cytology (US-FNAC) can be used to further diagnose nodules that cannot be diagnosed by ultrasonography.
Extramedullary hematopoiesis (EH) can occur in tissues and organs of the body due to disease, insufficient blood supply, or insufficient bone marrow function. EH usually occurs in organs such as the embryonic liver, spleen, and lymph nodes and is rare in mature thyroid tissue. Some of the patients with extramedullary hematopoiesis found in thyroid tissue had chronic anemic diseases such as mye-lofibrosis or iron deficiency anemia,9–11 while others had no hematopoiesis.12
To our knowledge, this is the first report of Hashimoto’s thyroiditis with EBF. This patient was preoperatively diagnosed with papillary carcinoma of the left thyroid lobe and cervical lymph node metastasis was not excluded. During the operation, it was found that the left and right thyroid nodules were extremely hard and did not invade the surrounding tissues. Postoperative pathological findings are complex: The Bilateral thyroid lobes are indicative of HT. Calcification and ossification of the left lobe with bone marrow formation in the ossified area. Focal epithelial papillary hyperplasia, combined with morphology and immunohistochemistry, tends to papillary thyroid microcarcinoma (0.3 cm). Lymph node biopsy showed reactive hyperplastic changes.
Osseous metaplasia and heterotopic bone formation are complex processes which precise mechanisms remain elusive. Bone morphogenetic protein (BMP) is a group of proteins that are found in demineralized bone and are of the major contributors to bone formation, inducing local ossification and synthesizing a ground substance and collagen. Full maturation into lamellar bone also requires adequate calcium and phosphate concentrations, which are critical to the mineralization process.5 BMPs are a family of metalloproteinases with at least 30 members. BMPs 1–7 are involved in ectopic bone formation. For instance, BMP-1 converts various precursor proteins to mature or active forms and is involved in extracellular matrix formation.13 BMP-2 was found to be highly expressed in calcified thyroid tissue.14
In conclusion, the Hashimoto’s thyroiditis (HT) nodule with OM and EBF reported in this case is a rare thyroid tissue metaplasia. Based on the reviewed literature, it has never been reported before. The pathogenesis of OM and EBF is currently not fully elucidated and requires ongoing research.
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
This study was supported by the National Natural Science Foundation of China (82070288), the Health Commission of Sichuan Province (21PJ100), the Talent Development Project of The Affiliated Hospital of Southwest Medical University (20062).
Bo-Tao Zhang https://orcid.org/0000-0003-0299-8575
Jun Jiang https://orcid.org/0000-0003-1292-7236
1 The Department of General Surgery (Department of Thyroid Surgery), The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
† These authors contributed equally to this work.
Corresponding Author:
Jiang Jun, The Department of General Surgery (Department of Thyroid Surgery), The Affiliated Hospital of Southwest Medical University, No. 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, China.
Email: jiangjun@swmu.edu.cn
