Thyroid Embryonic Anomalies Involving the Medial and Lateral Anlagen: Two Surgical Case Reports

Figure 5

Thyroid rests types I-IV. Type I: a protrusion of thyroid tissue from the inferior of the thyroid gland and distinct from the lower border of the thyroid lobe. Type II: thyroid tissue within the thyrothymic tract and attached to the thyroid by a narrow pedicle of thyroid tissue. Type III: thyroid tissue similar to type II but attached to the thyroid gland by a fibrovascular core. Type IV: has no thyroid gland connection [14].