Immunohistochemical PAX-8 positivity may represent thyroid tumors, kidney tumors, ovarian tumors, etc. PAX-8 belongs to the family of transcription factor paired-box genes that are involved in regulating organogenesis in the thyroid, kidney, and mullerian duct system. Immunohistochemical PAX-8 positivity usually represents epithelial tumors in the thyroid and parathyroid glands, kidneys, thymus, and female genital tract. In addition to this, PAX8 expression has also been reported to occur in certain neuroendocrine tumors, including highly differentiated pancreatic neuroendocrine tumors, duodenal and rectal carcinoid tumors, and B-cell lymphomas. When immunohistochemistry is performed and PAX8 positivity is present, one should go to a regular hospital for consultation and treatment under the guidance of a doctor.