[Histological and immunohistochemical characteristics of ACTH-secreting tumors].

The histological and immunohistochemical characteristics of pituitary (corticotropinomas) and nonpituitary adrenocorticotropic hormone (ACTH)-secreting neuroendocrine tumors (NET) were comparatively analyzed. The study included 46 corticotropinomas and 37 ectopic ACTH-secreting tumors. Removed NET tissue was investigated using routine histological and immunohistochemical techniques. A study of the morphofunctional characteristics of removed NETs yielded the following data: their ability to express ACTH, growth hormone, luteinizing hormone, follicle-stimulating hormone, and prolactin in both in pituitary and nonpituitary NET tumors. Angiogenic markers (CD31 and VEGF) were found in equal frequency. The histological structure of all corticotropinomas suggested their benign origin while nonpituitary NETs had different morphological structures, malignancy and invasiveness grades, and metastatic properties. The highest cell proliferation potential (Ki-67) was discovered in NET in ectopic ACTH syndrome as compared to corticotropinomas.