Diseases of the pineal gland

The epiphysis consists of a loose neuroglial stroma that surrounds the nests of epithelial cells containing neurosecretory granules, these cells are called pineocytes. Pineocytes have long thin processes, which are remnants of primitive predecessors of neurons. These islets of pineocytes are intertwined with islands of glial cells (astrocytes). The function of the pineal gland has not been studied to date. The pineocytes secrete two hormones of the regulator into the blood: melatonin and serotonin. What is unusual is that these substances are not secreted at the same time: only melatonin is synthesized at night, and during the daytime it is serotonin. Melatonin inhibits the development of the reproductive system until a certain age. Another function of melatonin is the effect on skin pigmentation; under its influence, aggregation of melanin granules in the melanophores of the epidermis is noted,whereby the skin brightens, i.e. develops the effect of the opposite action of the melan-stimulating hormone of the pituitary gland.
Diseases of the pineal gland are clearly not well understood. Among them, the main importance are tumors, which are called pinealomas; they are divided into two types: pineoblastoma (malignant tumors) and pineocytoma (benign).

Pineoblastomas are found in young people, macroscopically have the appearance of soft crumbling gray lesions with hemorrhages and necrosis. Tumors can grow into the tissues surrounding the epiphysis (hypothalamus, midbrain, bottom of the third ventricle). Histologically, pineoblastomas consist of polymorphic cells 2-4 times as large as red blood cells. Characterized by hyperchromia of the nuclei, high mitotic activity, found sockets of tumor cells. Pineoblastoma is characterized by metastasis of the cerebrospinal fluid pathways.

Macroscopically pineocytomas are gray or hemorrhagic formations that squeeze, but do not infiltrate, the surrounding structures. Microscopically revealed glial and neuronal differentiation. Such cells immunohistochemically stained for glial fibrillary acidic protein. The tumor can squeeze the sylviae aqueduct, leading to the development of internal hydrocephalus. In children in the pineal region, fetal tumors of the central nervous system can be detected.
In endocrine glands, the development of multiple endocrine neoplasia (MEH) is characteristic – a group of hereditary diseases in which hyperplasia or a tumor develops in more than one endocrine gland. The pathogenesis of MEN syndromes remains unclear. At the same time, it has been established that they are associated with autosomal mutations, usually dominant. In all these diseases, structures of neuroectodermal origin are involved in the process.
MENH I (Vermera syndrome) includes multiple parathyroid and pancreatic adenomas.
MEN syndrome 2a (Sippl syndrome) includes medullary thyroid cancer, adrenal pheochromocytoma, parathyroid adenomas.
MENH type III (MEN syndrome 2b) – a syndrome of mucous neuroma. It is characterized by the presence of medullary thyroid cancer, adrenal pheochromocytoma and neuroma (or ganglioneuroma) of the eyelids, mouth, respiratory tract, gastrointestinal tract and bladder. In addition, morphan-like status and hyperplasia of the parathyroid glands are noted.

local_offerevent_note January 1, 2020

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