</gallery>
===Resident Questions===* <spoiler text="Diagnosis?">* Lymphocytic thyroiditis (Hashimoto thyroiditis). </spoiler>
* <spoiler text="What are the clinical findings that support this diagnosis?">
* The diagnosis of Hashimoto is based on one or more circulating autoantibodies. The most common are anti-thyroglobulin and anti-thyroid peroxidase (TPO).
</spoiler>
==Cytologic Features==
* Hurthle cells with intermingled lymphocytes.
* Often colloid is rare or absent.
* Large lymphoid aggregates with germinal centers.
==Additional Teaching Points==
===Immunohistochemistry===
* TTF-1 (nuclear stain)
** Thyroid Transcription factor1 regulates transcription of genes specific to the thyroid, lung, and diencephalon
** If metastatic thyroid cancer to the lung is ruled out by morphology or +thyroglobulin; then a +TTF1 supports adenocarcinoma originating from the lung
* P63 (nuclear stain) and 34BE12 (cytoplasmic stain)
** Used for squamous differentiation
* TTF1 is more sensitive than p63
** If a tumor stains for both it is more likely to be adenocarcinoma
* Napsin A(cytoplasmic stain)
** Granular staining pattern
** Marker for adenocarcinoma
{{Cytologically Yours}}
