• Micropapillary carcinoma of the thyroid
  • Clear cell renal cell carcinoma
  • Ovarian serous LMP

Pax8 is a nuclear transcription factor involved in Mullerian organogenesis.


  • Paired box gene 8


Technical InfoEdit

Staining PatternEdit

  • Nuclear (like all transcription factors)

Expression in Normal TissuesEdit

  • Renal tubules[1]
  • Fallopian tubes[1]

Expression in Neoplastic EntitiesEdit

  • Thyroid adenoma[2]

Intermediate/Uncertain Malignant PotentialEdit

  • Ovarian carcinomas (87%), including serous, clear cell, and endometrioid carcinomas. Less than 10% of mucinous ovarian carcinomas stain, however.[3]
  • Papillary carcinoma of the thyroid[2]
  • Clear cell renal cell carcinoma[4]
  • Anaplastic thyroid carcinoma[1]

Expression in Non-Neoplastic EntitiesEdit

Pertinent NegativesEdit

This antigen is typically NOT expressed by the following entities:

  • Breast carcinoma
  • Pulmonary carcinoma[1]

Practical Uses / PanelsEdit

  • Useful to differentiate anaplastic thyroid carcinoma (Pax8+) from pulmonary adenocarcinoma (Pax8-)[1]

Common PitfallsEdit

Related Links/Other ResourcesEdit


  1. 1.0 1.1 1.2 1.3 1.4 Mod Pathol. 2008 Feb;21(2):192-200.
  2. 2.0 2.1 Fabbro D, Di LorentoC, Alberto Beltrami C, Belfiore A, Di Lauro R, Damante G. Expression of thyroid-specific transcription factors TTF-1 and PAX-8 in human thyroid neoplasms. Cancer Research 1994;54:4744-9
  3. Am J Surg Pathol. 2008 Oct;32(10):1566-71.
  4. Sangoi A, Karamchandani J, Kim J, Pai R, McKeeney J. The use of immunohistochemistry in the diagnosis of metastatic clear cell renal cell carcinoma: A review of PAX-8, PAX-2, hKIM-1, RCCma, and CD10. Adv Anat Pathol. 2010;17(6);377-93

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