Figure 2

Photomicrograph comparison of the histological and immunohistochemical features of the adrenocorticotrophic hormone (ACTH)-secreting pituitary tumor and its metastasis to the liver (carcinoma). A: Pituitary tumor composed of uniform cells with abundant cytoplasm. Mitotic figures are not observed. B: Tumor showing peripheral cytoplasmic ACTH immunoreactivity. C through D: Pituitary carcinoma with liver metastases. The hepatic nodule shows immunohistochemical reactivity for ACTH and chromogranin A (CgA). H&E (A) and immunoperoxidase staining for ACTH (B and C) and chromogranin A (D). Original magnification × 40 (A), × 10 (B), × 4 (C-D).