Pituitary adenoma is a benign tumor formation originating from the glandular tissue of the anterior pituitary gland. Clinically, pituitary adenoma is characterized by ophthalmic-neurological syndrome (headache, oculomotor disorders, double vision, narrowing of the visual fields) and endocrine-metabolic syndrome, in which, depending on the type of pituitary adenoma, gigantism and acromegaly, galactorrhea, sexual dysfunction, hypercorticism, hypo- or hyperthyroidism, hypogonadism can be observed. The diagnosis of “pituitary adenoma” is established on the basis of radiography and CT of the Turkish saddle, MRI and brain angiography, hormonal studies and ophthalmological examination. Pituitary adenoma is treated by radiation exposure, radiosurgical method, as well as by transnasal or transcranial removal.
D35.2 Pituitary adenoma
Pituitary adenoma is a pituitary tumor originating in the tissues of its anterior lobe. It produces 6 hormones that regulate the function of the endocrine glands: thyrotropin (TSH), somatotropin (STH), follitropin, prolactin, lutropin and adrenocorticotropic hormone (ACTH). According to statistics, pituitary adenoma accounts for about 10% of all intracranial tumors found in neurological practice. Pituitary adenoma occurs most often in middle-aged people (30-40 years).
Reasons of pituitary adenoma
The etiology and pathogenesis in modern medicine remain the subject of research. It is believed that neoplasm can occur when exposed to such provoking factors as traumatic brain injuries, neuroinfections (tuberculosis, neurosyphilis, brucellosis, polio, encephalitis, meningitis, brain abscess, cerebral malaria, etc.), adverse effects on the fetus during its intrauterine development. Recently, it has been noted that pituitary adenoma in women is associated with prolonged use of oral contraceptive drugs.
Studies have shown that in some cases pituitary adenoma occurs as a result of increased hypothalamic stimulation, which is a reaction to the primary decrease in hormonal activity of the peripheral endocrine glands. A similar mechanism of the occurrence of adenoma can be observed, for example, in primary hypogonadism and hypothyroidism.
Clinical neurology divides pituitary adenomas into two large groups: hormonally inactive and hormonally active. Pituitary adenoma of the first group does not have the ability to produce hormones and therefore remains exclusively under the jurisdiction of neurology. Disease of the second group, like pituitary tissues, produces pituitary hormones and is also a subject of study for endocrinology. Depending on the secreted hormones, hormonally active pituitary adenomas are classified into:
- somatotropic (somatotropinomas)
- prolactin (prolactinomas)
- corticotropic (corticotropinomas)
- thyrotropic (thyrotropinomas)
- gonadotropic (gonadotropinomas).
Depending on its size, pituitary adenoma can refer to microadenomas – tumors with a diameter of up to 2 cm or macroadenomas with a diameter of more than 2 cm.
Symptoms of pituitary adenoma
Clinically, pituitary adenoma is manifested by a complex of ophthalmic and neurological symptoms associated with the pressure of a growing tumor on intracranial structures located in the area of the Turkish saddle. If the pituitary adenoma is hormonally active, then the endocrine-exchange syndrome may come to the fore in its clinical picture.
Changes in the patient’s condition are often associated not with the hyperproduction of the tropic pituitary hormone itself, but with the activation of the target organ on which it acts. The manifestations of endocrine exchange syndrome directly depend on the nature of the tumor. On the other hand, pituitary adenoma may be accompanied by symptoms of panhypopituitarism, which develops due to the destruction of pituitary tissue by a growing tumor.
Ophthalmic neurological syndrome
The ophthalmic and neurological symptoms that accompany pituitary adenoma largely depend on the direction and prevalence of its growth. As a rule, these include headache, visual field changes, diplopia and oculomotor disorders. The headache is caused by the pressure that the pituitary adenoma exerts on the Turkish saddle. It has a blunt character, does not depend on the position of the body and is not accompanied by nausea.
Patients often complain that they do not always manage to relieve headaches with the help of analgesics. The headache accompanying pituitary adenoma is usually localized in the frontal and temporal regions, as well as behind the eye socket. There may be a sharp increase in headache, which is associated either with hemorrhage in the tumor tissue, or with its intensive growth.
The limitation of the fields of vision is caused by compression of the growing adenoma of the intersection of the optic nerves located in the area of the Turkish saddle under the pituitary gland. A long-term pituitary adenoma can lead to the development of optic nerve atrophy. If the pituitary adenoma grows laterally, then over time it compresses the branches of the III, IV, VI and V cranial nerves.
As a result, there is a violation of oculomotor function (ophthalmoplegia) and double vision (diplopia). There may be a decrease in visual acuity. If disease sprouts the bottom of the Turkish saddle and spreads to the latticed or wedge-shaped sinus, then the patient has a nasal congestion that mimics the clinic of sinusitis or nasal tumors. The growth upward causes damage to the structures of the hypothalamus and can lead to the development of disorders of consciousness.
Endocrine exchange syndrome
Metabolic and endocrine disorders are characteristic of adenomas that actively produce hormones. Clinical manifestations correspond to the type of pituitary hormone produced by the tumor. The following clinical options are possible:
- Somatotropinoma is adenoma that produces STH, in children it is manifested by symptoms of gigantism, in adults – acromegaly. In addition to the characteristic changes in the skeleton, patients may develop diabetes mellitus and obesity, an enlargement of the thyroid gland (diffuse or nodular goiter), usually not accompanied by its functional disorders. Hirsutism, hyperhidrosis, increased greasiness of the skin and the appearance of warts, papillomas and nevi on it are often observed. It is possible to develop polyneuropathy, accompanied by pain, paresthesia and a decrease in the sensitivity of the peripheral parts of the extremities.
- Prolactinoma is a pituitary adenoma that secretes prolactin. In women, it is accompanied by a violation of the menstrual cycle, galactorrhea, amenorrhea and infertility. These symptoms may occur in combination or be observed in isolation. About 30% of women with prolactinoma suffer from seborrhea, acne, hypertrichosis, moderate obesity, anorgasmia. In men, ophthalmic and neurological symptoms usually come to the fore, against which galactorrhea, gynecomastia, impotence and decreased libido are observed.
- Corticotropinoma – adenoma, producing ACTH, is detected in almost 100% of cases of Itsenko-Cushing’s disease. The tumor manifests itself with classic symptoms of hypercorticism, increased skin pigmentation as a result of increased production along with ACTH and melanocytostimulating hormone. Mental abnormalities are possible. A feature of this type of pituitary adenoma is a tendency to malignant transformation followed by metastasis. The early development of serious endocrine disorders contributes to the detection of the tumor before the appearance of ophthalmic and neurological symptoms associated with its increase.
- Thyrotropinoma is adenoma that secretes TSH. If it is of a primary nature, it is manifested by symptoms of hyperthyroidism. If it occurs a second time, then hypothyroidism is observed.
- Gonadotropinoma is adenoma that produces gonadotropic hormones, has nonspecific symptoms and is detected mainly by the presence of typical ophthalmic and neurological symptoms. In its clinical picture, hypogonadism can be combined with galactorrhea caused by hypersecretion of prolactin by the pituitary tissues surrounding the adenoma.
Patients whose pituitary adenoma is accompanied by a pronounced ophthalmic-neurological syndrome, as a rule, seek help from a neurologist or ophthalmologist. Patients with pituitary adenoma manifested by endocrine-metabolic syndrome are more likely to come to an appointment with an endocrinologist. In any case, patients with suspected pituitary adenoma should be examined by all three specialists.
In order to visualize the adenoma, an X-ray of the Turkish saddle is performed, which reveals bone signs: osteoporosis with the destruction of the back of the Turkish saddle, a typical double-contour of its bottom. Additionally, pneumocysternography is used, which determines the displacement of the chiasmal tanks from their normal position.
More accurate data can be obtained during CT of the skull and MRI of the brain, CT of the Turkish saddle. However, about 25-35% of pituitary adenomas are so small that their visualization is not possible even with modern tomography capabilities. If there is reason to believe that the pituitary adenoma is growing towards the cavernous sinus, an angiography of the brain is prescribed.
Hormonal studies are of great importance in the diagnosis. Determination of the concentration of pituitary hormones in the blood is carried out by a specific radiological method. Depending on the symptoms, the hormones produced by the peripheral endocrine glands are also determined: cortisol, T3, T4, prolactin, estradiol, testosterone.
Ophthalmological disorders, which are accompanied by pituitary adenoma, are detected during ophthalmological examination, perimetry, visual acuity testing. To exclude eye diseases, ophthalmoscopy is performed.
Treatment of pituitary adenoma
Conservative treatment can be applied mainly to small-sized prolactinomas. It is carried out by prolactin antagonists, for example, bromocriptine. With small adenomas, it is possible to use radiation methods of influencing the tumor: gamma therapy, remote radiation or proton therapy, stereotactic radiosurgery – the introduction of a radioactive substance directly into the tumor tissue.
Patients whose pituitary adenoma is large and / or accompanied by complications (hemorrhage, visual impairment, formation of a brain cyst) should consult a neurosurgeon to consider the possibility of surgical treatment. The operation to remove the adenoma can be performed by the transnasal method using endoscopic technique. Macroadenomas are to be removed by the transcranial method – by trepanation of the skull.
This disease refers to benign neoplasms, however, with an increase in size, it, like other brain tumors, takes a malignant course due to compression of the anatomical formations surrounding it. The size of the tumor also determines the possibility of its complete removal. Pituitary adenoma with a diameter of more than 2 cm is associated with the probability of postoperative relapse, which can occur within 5 years after removal.
The prognosis of adenoma also depends on its type. Thus, with microcorticotropinomas, 85% of patients have a complete restoration of endocrine function after surgical treatment. In patients with somatotropinoma and prolactinoma, this indicator is significantly lower — 20-25%. According to some data, on average, after surgical treatment, recovery is observed in 67% of patients, and the number of relapses is about 12%. In some cases, self-healing occurs with hemorrhage into the adenoma, which is most often observed with prolactinomas.