Mature bony metaplasia in multinodular goiter: A case report

INTRODUCTION: Various degenerative changes can be seen in multinodular goiter. These include cystic changes, hemorrhage, fibrosis and calcification. However, osseous metaplasia is extremely rare. PRESENTATION OF THE CASE: Here we present a 44-year-old lady with multiple ill-defined thyroid nodules upon physical examination. Thyroid ultrasound showed multiple variably sized nodules with cystic degeneration. The largest left lobe nodule showed macrocalcification. Further evaluation was advised by the radiologist. Total thyroidectomy was performed and it revealed histological osseous metaplasia with lamellar bone formation. The clinical course following resection was unremarkable. DISCUSSION: Osseous metaplasia with ectopic bone formation is extremely rare in benign thyroid disorders. To the best of our knowledge, only thirteen cases of sporadic goiter with heterotopic bone formation are reported. CONCLUSION: Osseous metaplasia can be a pitfall in the diagnosis of multinodular goiter. Ruling out comorbidities is mandatory, and further genetic and follow-up studies are needed.