Goiter is the enlargement of the thyroid gland. It may be diffuse, multinodular, single nodule.

Diffuse Goiter
Smooth, irregular and firm gland. Right lobe is larger than the left. It is usually due to Graves' disease (diffuse toxic goiter), iodine deficiency, Hashimoto's thyroiditis. Systolic bruit generally indicates diffuse toxic goiter (bell of the stethoscope).

Multinodular Goiter
Presence of multiple palpable nodules. May be due to simple colloid goiter, neoplasms, thyroiditis, etc.

Single Nodule
It may be a cyst, an area of hemorrhage, a neoplasm (benign/malignant).