Editing Hashimoto's thyroiditis (section)

=== Pathology ===
[[File:Hashimoto's thyroiditis, HE 3.jpg|thumb|Marked lympocytic infiltration (purple areas) of the thyroid gland in a patient with chronic autoimmune thyroiditis]]
[[File:Hashimoto thyroiditis -- high mag.jpg|thumb|High powered magnification showing lymphocytic infiltration of the thyroid gland in autoimmune thyroiditis]]
Gross pathology of a thyroid with autoimmune thyroiditis may show an symmetrically enlarged thyroid.<ref name="Ramos-Levi2023" /> It is often paler in color, in comparison to normal thyroid tissue which is reddish-brown.<ref name="Ramos-Levi2023" /> 

Microscopic examination ([[histology]]) will show lymphocytes (including [[Plasma cell|plasma B-cells]]) diffusely infiltrating the [[parenchyma]].<ref name="Maitra 2014 The Endocrine System" /> The lymphocytes are predominately T-lymphocytes with a representation of both [[CD4+ cells|CD4+]] and [[CD8+]] cells.<ref name="Ramos-Levi2023" /> The plasma cells are [[Polyclonal B cell response|polyclonal]], with present [[Germinal center|germinal centers]] resembling the structure of a [[lymph node]]<ref name="Ramos-Levi2023" /> (also called secondary lymphoid follicles, not to be confused with the normally present [[colloid]]-filled [[Thyroid follicle|follicles]] that constitute the thyroid).<ref name="Maitra 2014 The Endocrine System" /> 

In late stages of the disease, the thyroid may be [[Atrophy|atrophic]].<ref name="Mincer2022" /> Colloid-filled follicles shrink and the cuboidal cells that usually line the follicles become [[Hürthle cell|Hürthle cells]].<ref name="Ramos-Levi2023" /> Fibrous tissue may be found throughout the affected thyroid as well.<ref name="Ramos-Levi2023" /> Severe thyroid atrophy presents often with denser fibrotic bands of [[collagen]] that remains within the confines of the thyroid capsule.<ref name="Maitra 2014 The Endocrine System" /> 

Generally, pathological findings of the thyroid are related to the amount of existing thyroid function — the more infiltration and fibrosis, the less likely a patient will have normal thyroid function.<ref name="Ramos-Levi2023" /> A rare but serious complication is [[thyroid lymphoma]], generally the B-cell type, [[non-Hodgkin lymphoma]].<ref name="Dayan96" />