Hemithyroid Agenesis with Hyperthyroidism

A 27-year-old patient came in with history of swelling in the neck on the right side. Ultrasound scan showed enlarged diffusely hypoechoic right lobe of thyroid with increased vascularity. Left lobe and isthmus were absent. No previous history of hemithyroidectomy. Thyroid function tests showed hyperthyroidism.

Figure 1: Absent left lobe of thyroid and isthmus

Figure 2: Absent left lobe of thyroid and isthmus

Figure 3: Enlarged diffusely hypoechoic right lobe

Figure 4: Right thyroid lobe with increased vascularity

Figure 5: Right thyroid lobe with increased vascularity

Discussion: Hemithyroid agenesis is a rare congenital anomaly of thyroid has found to be three times more common in females as compared to males. In 80 percent, the left thyroid lobe is absent and about 50 percent of patients with left hemithyroid agenesis will also have an absent thyroid isthmus.

Many times, the patient is found to have hemiagenesis of a thyroid lobe incidentally. Coexisting thyroid disorders in the remaining lobe are a common occurrence with hemiagenesis.

Disorders that haven reported in the remnant thyroid lobe include hyperthyroidism, hypothyroidism, multinodular goiter, chronic thyroiditis, adenocarcinoma, and papillary thyroid carcinoma. Hyperthyroidism is the most prevalent disorder associated with thyroid hemiagenesis. In fact, many cases of hemiagenesis discovered upon workup of the hyperthyroidism.

Harpreet Singh, MD, JP Scan private diagnostic center, Khanna, Punjab, India