Insular thyroid carcinoma in the background of follicular thyroid carcinoma: A report of a rare case and mini‑review of the literature

Follicular thyroid carcinoma (FTC) is a well-differentiated malignancy, while insular thyroid carcinoma (ITC) is a very rare and poorly differentiated tumor. The present study reports a case of ITC arising within the background of FTC. A 52-year-old housewife presented with an anterior neck swelling for a duration of 6 months.

An ultrasound examination revealed a well-defined solid nodule measuring ~58x37x28 mm in the mid-lower third of the right thyroid lobe, and two small nodules of <3 mm in size in the left lobe. Fine needle aspiration cytology of the lesion led to the suspicion of follicular neoplasm. A right thyroid lobectomy was performed, and the histopathological examination revealed poorly differentiated insular carcinoma arising in the background of FTC.

As a result of this diagnosis, a completion thyroidectomy was performed. ITC is a rare and highly aggressive thyroid malignancy that is morphologically and …