• All IHC stains will include a positive control tissue

•  Pit-1 immunostain is useful for diagnosis of the family of pituitary adenomas that display development along the Prolactin-Growth Hormone-TSH spectrum
• It is also present within normal anterior pituitary gland, so the presence of pituitary adenoma must be confirmed on H&E stains (occasionally with the support of ancillary stains such as reticulin stains for normal adenohypophyseal architecture).

Note: Pit-1 should generally be used in conjunction with other pituitary stains to help subtype pituitary adenomas.

Submit a formalin-fixed, paraffin embedded tissue block

Formalin-fixed, paraffin embedded (FFPE) tissue block

FFPE tissue section mounted on a charged, unstained slide

Ambient (preferred)

• Unlabeled/mislabeled block
• Insufficient tissue
• Slides broken beyond repair

Immunohistochemical staining and microscopic examination

If requested, an interpretive report will be provided

Specifications

• The PIT-1 gene encodes a transcription factor involved in anterior pituitary development, where it is expressed in cell types responsible for prolactin, growth hormone and beta thyroid stimulating hormone (beta-TSH, also known as beta-thyrotropin) production
• The antibody to the protein Pit-1 reacts with this transcription factor in normal adenohypophysis and in pituitary adenomas, which show development along this line
• Hence, pituitary adenomas that produce prolactin, growth hormone or beta-TSH (or combinations thereof), are expected to be positive using this stain^{1, 2}

 Staining pattern

• Strong nuclear staining is observed within lactotrophs, somatotrophs, mammosomatotrophs, thyrotrophs and pituitary adenomas that develop along these lines of differentiation

References:

1. Friend KE, Chiou YK, Laws ER, Jr., Lopes MB, Shupnik MA. Pit-1 messenger ribonucleic acid is differentially expressed in human pituitary adenomas. J Clin Endocrinol Metab. 1993;77(5):1281-6.
2. Pellegrini I, Barlier A, Gunz G, Figarella-Branger D, Enjalbert A, Grisoli F, et al. Pit-1 gene expression in the human pituitary and pituitary adenomas. J Clin Endocrinol Metab. 1994;79(1):189-96.