Cytologically Yours: Unknowns: 201311: Case 1

Clinical History

45 year old female with hypothyroidism.

Cytology

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Resident Questions

• Diagnosis?

Lymphocytic thyroiditis (Hashimoto thyroiditis).

• 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).

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