These diseases can be associated with its tumors, autoimmune disorders, inflammation, necrosis, or develop as a result of damage to the hypothalamus or other parts of the CNS.
Tumors. Various primary tumors can develop in the pituitary gland, both benign and malignant. The most common tumor of the pituitary gland is an adenoma – a benign tumor of various types of endocrine cells of the anterior pituitary gland. There are macroadenomas (more than 1 cm in diameter) and microadenomas (less than 1 cm in diameter). Microscopically distinguish the diffuse type, when tumor cells grow in a continuous array among a network of small vessels, and a sinusoidal type, in which the cells are located near numerous capillaries, sometimes pseudo-sockets or glandular structures form.
The division of pituitary adenomas into acidophilic, basophilic, chromophobic, and mixed is generally accepted. At the present stage, it has become obvious that this classification does not quite correspond to the clinical manifestation of pituitary adenomas. Modern methods of pathology (IHC and EM) made it possible to classify adenomas by the type of hormones produced by these tumor cells.
One of the most frequent tumors is somatotropic adenoma, which is characterized by GH hypersecretion, which leads to the development of gigantism or acromegaly. Microscopically, this tumor is formed by large, densely granular acidophilic or redigranular acidophilic and chromophobic cells.
Mixed prolactino-somatotropic adenoma causes a clinical picture characteristic of both prolactotropic and somatotropic adenoma.
In patients with gonadotropic adenoma, hypogonadism and obesity are observed. Plurimormonic adenoma is characterized by a variegated clinical picture, but acromegaly and hyperlactinemia occur constantly.
The hormone-inactive pituitary adenomas include oncocyte adenoma and undifferentiated adenoma.
In the neurohypophysis, tumors grow very rarely. These include astrocytoma and ependymoma. Histologically, neurohypophysis tumors do not present any features compared with similar tumors located in other parts of the CNS.
Symmonds disease (pituitary cachexia). The disease is manifested by progressive cachexia, atrophy of internal organs, decreased function of the sex glands. The disease is observed mainly in women at a young age, often after childbirth.Morphologically, foci of necrosis are found in the anterior pituitary gland because of vascular embolism or scars at the site of necrosis foci. Other causes of pituitary necrosis (in addition to embolism) include hemorrhage, thrombosis of the cavernous sinuses, radiation injury to the pituitary gland, and periarteritis nodosa.
Pituitary dwarf growth (pituitary nanism) occurs in the pituitary of the pituitary (aplasia, hypoplasia) or in the destruction of its tissue in childhood due to inflammation or necrosis. Clinically, patients have a general underdevelopment with preserved proportionality of addition; genitals are usually underdeveloped.
Diabetes insipidus (diabetes insipidus) is a chronic disease, the main clinical manifestations of which are excruciating thirst (polydipsia) and polyuria, usually from 3 to 12 liters.
The disease is caused by pathological processes that lead to dysfunction of the hypothalamic-pituitary system, deficiency of antidiuretic hormone (vasopressin). This hormone is produced in the supra-optic nuclei of the hypothalamus, along the axons of the cells of the supra-optic hypophysial tract, it enters the posterior lobe of the pituitary gland, from which it is released into the bloodstream. A decrease in the level of vasopressin in the blood leads to a decrease in the reabsorption of water in the distal regions of the convoluted tubules of the kidneys.
Among the pathological processes leading to diabetes insipidus, the main significance are tumors of the sellar area and inflammatory processes in the same area.
Of the tumors in the sellar region, the craniopharyngioma is the most common, which belongs to dysontogenetic tumors, which develop from the remaining rudiments of the pituitary pouch. This tumor occurs mainly in children and young people, it is localized mainly above the Turkish saddle, but can sometimes be located anterior or posteriorly from it. The tumor grows slowly, expansively, squeezing the surrounding brain tissue. Macroscopically, a craniopharyngioma can be in the form of a cyst filled with a brown fluid such as lube in which cholesterol crystals are found. Microscopically, the tumor remotely resembles an odontogenous tumor adamantine, in connection with which, this variant of the structure is called adamantinous. Epithelial cells in their shape and location resemble a developing enamel organ of the tooth germ.
Another histological variant is papillary craniopharyngioma. Macroscopically has the form of an encapsulated node located in the third ventricle. Histologically, the tumor consists of solid layers of differentiated epithelial cells, separated by fibrovascular stroma. This histological variant of the tumor resembles basalioma in structure.
Itsenko-Cushing disease. The disease was first described in 1925 by Itsenko, who established the primary lesion of the diencephalon. Later (1932), Cushing showed that the leading cause of the disease is the basophilic adenoma of the anterior pituitary gland, and called it pituitary basophilism.
Symptoms characteristic of Itsenko-Cushing’s disease can be with tumors of the adrenal cortex, much less often – the lungs, thymus, pancreas. In such cases, this clinical symptom complex is called Itsenko-Cushing syndrome.
Appearance of patients with Itsenko-Cushing’s disease (syndrome): moon-shaped face, upper type obesity (mainly the face and torso, with relatively thin limbs), arterial hypertension, on the skin of the thighs, abdomen, chest – blue-purple stretch bands. In women, excessive viril hairiness is observed (mainly of fluff nature), menstrual disorders, in men, impotence.
The Babinsky-Fröhlich disease (adiposogenital dystrophy) is characterized by progressive obesity, underdevelopment of the genitals and a decrease in the function of the sex glands. The basis of the disease are pathological changes in the pituitary and hypothalamus of a tumor or infectious nature (mainly in the posterior lobe of the pituitary). The disease can be combined with hypothyroidism, diabetes insipidus, adrenal insufficiency.