Intranuclear Cytoplasmic Pseudoinclusions in Pituitary Adenomas

Abstract

Intranuclear pseudoinclusions are well known in papillary carcinomas of the thyroid gland, hepatocellular carcinomas, meningiomas, paragangliomas, pheochromocytomas, and melanomas. Only two papers on the intranuclear inclusions of adenohypophyseal cells in humans have been reported. This study found that intranuclear cytoplasmic pseudoinclusions occur frequently in pituitary adenoma cases (70.3%, 97 of 138 pituitary adenomas) and are uncommon in normal pituitary tissue (11.1%, 1 of 9 normal pituitary tissues). In addition, the frequency of intranuclear cytoplasmic pseudoinclusions between the functional and non-functional pituitary adenomas was found to be similar. Electron microscopy and immunostaining was used to reveal the entity of the intranuclear inclusion. These intranuclear inclusions are due to cytoplasmic invagination because 1) the inclusions are continuous with the cytoplasm, 2) all cytoplasmic organelles, such as the endoplasmic reticulum, the Golgi apparatus, and the secretory granules are found in the inclusions, 3) immunoreactivity of the intranuclear inclusion is the same as that of the cytoplasm. In conclusion, intranuclear cytoplasmic pseudoinclusions in pituitary adenomas occur frequently (70.3%) and are formed by cytoplasmic invagination. This study suggests that pituitary intranuclear inclusions caused by cytoplasmic invagination be called "intranuclear cytoplasmic pseudoinclusions".

Dysplastic Hepatocytes Develop Nuclear Inclusions in a Mouse Model of Viral Hepatitis

“…These inclusions are associated with various clinical conditions including cancer, obesity, diabetes, nonalcoholic fatty liver disease, Wilson disease, and amiodarone toxicity and observed in many tissue types including liver [1], [2], [3], [4]. The origins of these inclusions are unknown, however their presence has been used in histo-pathological diagnosis.…”

Nuclear pseudoinclusions in melanoma cells: prognostic fact or artifact? The possible role of Golgi phosphoprotein 3 overexpression in nuclear pseudoinclusions generation

“…It is critical to remember that biotin inclusions, described in several tumors, cause false‐positive immunostaining reactions in avidin–biotin‐based detection protocols . Pseudoinclusions are classically found in papillary thyroid carcinoma and meningioma, but can occur in a number of other malignant and benign lesions, including usual ductal hyperplasia of the breast or pituitary adenoma . Appreciation of NPIs during evaluation of brain tumors strongly supports a diagnosis of meningioma over other entities .…”

A Case Report of Feline Pituitary Carcinoma with Hypercortisolism

“…These intranuclear inclusions are found in not only pituitary tumors [20] but also other tumors including meningioma [21], paraganglioma [4], phenochromocytoma [4] and thyroid carcinoma [8] in humans. Intranuclear inclusions in pituitary tumors are formed by cytoplasmic invagination and composed of cytoplasmic organelles, such as rough endoplasmic reticulum, the Golgi apparatus and the secretory granules [20]. In addition, it was reported that there are no significant differences in the frequency of the intranuclear inclusions between the functional and non-functional pituitary tumors [20].…”

“…Intranuclear inclusions in pituitary tumors are formed by cytoplasmic invagination and composed of cytoplasmic organelles, such as rough endoplasmic reticulum, the Golgi apparatus and the secretory granules [20]. In addition, it was reported that there are no significant differences in the frequency of the intranuclear inclusions between the functional and non-functional pituitary tumors [20]. To our best knowledge, there is no report about intranuclear inclusions in pituitary tumors in cats.…”