Morphology Thyroid follicular<unk>  ranges in diameter from 3 cm on an average, but sometimes is larger (up to 10 cm) or smaller. The typical<unk>  is solitary, spherical and encapsulated lesion that is well demarcated from the surrounding parenchyma. The color ranges from gray-white to red-brown, depending upon # the cellularity of the<unk>  # the colloid content. Areas of hemorrhage, fibrosis, calcification, and cystic change, similar to what is found in multinodular goiters, are common in thyroid (follicular)<unk> , particularly in larger lesions. Types Almost all<unk> ta are follicular<unk> ta. Follicular<unk> ta can be described as "cold", "warm" or "hot" depending on their level of function. Histopathologically, follicular<unk> ta can be classified according to their cellular architecture and relative amounts of cellularity and colloid into the following types: *Fetal (microfollicular) - these have the potential for microinvasion. These consist of small, closely packed follicles lined with epithelium. *Colloid (macrofollicular) - these do not have any potential for microinvasion *Embryonal (atypical) - have the potential for microinvasion. *Hürthle cell<unk>  (oxyphil or oncocytic tumor) - have the potential for microinvasion. *Hyalinizing trabecular<unk>  Papillary<unk> ta are very rare. Differential diagnosis Most common causes of hyperthyroidism by age. A<unk>  is distinguished from a multinodular goiter of the thyroid in that an<unk>  is typically solitary, and is a neoplasm resulting from a genetic mutation (or other genetic abnormality) in a single precursor cell. In contrast, a multinodular goiter is usually thought to result from a hyperplastic response of the entire thyroid gland to a stimulus, such as iodine deficiency. Careful pathological examination may be necessary to distinguish a<unk>  from a minimally invasive follicular thyroid carcinoma.
Thyroid adenoma
Thyroid nodule
Papillary thyroid cancer
Thyroid lymphoma
Medullary thyroid cancer
Follicular thyroid cancer
Parathyroid adenoma
Thyroid neoplasm