Pituitary pathology. (A) Hematoxylin and eosin (H&E)–stained sections show a proliferation of epithelioid cells arranged in expanded nests and sheets. By immunohistochemistry, the tumor cells have a weak granular cytoplasmic staining for SHDB (B). The tumor cells are positive for transcription factor PIT1 (C) and negative for transcription factors SF1 (D) and TPIT (E). The tumor is also negative for prolactin (PRL, F), growth hormone (GH, G), and thyroid-stimulating hormone (TSH, H). Scale bar represents 50 µm.