PRL and neoplasm: Under a spectroscope, (Fig. 3) two types of tumor components were found; certain areas showed a nest-shaped distribution of the cell debris of the pituitary adenoma, and were positively stained for Syn and negatively stained for GH, luteinizing hormone (LH), prolactin (PRL), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH) and ACTH.