Pituitary adenoma

Pituitary adenomas (abbreviated H- adenomas) are benign tumors of the parenchyma cells of the anterior pituitary ( adenohypophysis ) and the posterior pituitary ( neurohypophysis ). They account for 10-15% of all intracranial neoplasms. Women are more likely (3:2) than men.

Clinical classification

The classification is the one based on the size in macro - and microadenomas. Measure they are referred to clinically as microadenoma less than 1 cm in diameter. Larger tumors are referred to as macroadenoma.

Radiological classification:

  • Grade 0: Small tumor in the pituitary gland
  • Grade I: Mild bulging with intact bony floor of the sella turcica
  • Grade II: floor intact, sella turcica more than 10 mm increased ( non- invasive)
  • Grade III: Partial destruction of the bony floor with penetration of the tumor into the sphenoid sinus ( invasive)
  • Grade IV: Complete destruction of the soil with diffuse infiltration of the sinus.

Extraselläre spreads upwards are classified depending on the penetration into symmetric (AC) and asymmetric (D E) enhancements.

Another classification is based on whether the tumors produce increased amounts of hormones. If they distribute pituitary hormones, they can be detected at this stage by the hormone side effects. Thus one distinguishes endocrine from hormoninaktiven adenomas.

Immunohistochemical classification:

  • Prolactinoma (prolactin -producing adenoma) 30% of cases
  • Manufacturing growth hormone ( somatotropin ) adenoma 10-20%
  • Mammosomatotropes adenoma ( somatotropin and prolactin )
  • Acidophilic Stammzelladenom
  • Kortikotropes adenoma (ACTH ) 10%
  • Gonadotropic adenoma (FSH -LH ) 10%
  • Adenoma thyroid stimulating hormone (TSH ) 1%
  • Plurihormonales adenoma
  • Null -cell adenoma / oncocytoma ( mitochondria- rich )

Symptoms

Symptoms of all pituitary tumors may have limitations of the visual field - or headaches - particularly bitemporal hemianopia the. If there is a compression of the III. Hirnventrikels, hydrocephalus can occur. Due to the mostly one-sided growth also endangers the cranial nerves are the oculomotor nerve ( eye muscle nerve) and the first two branches of the trigeminal nerve, the ophthalmic nerve and the maxillary nerve. A narrowing of the internal carotid artery may also be observed.

Side effects of hormonally active tumors arise from the effects of the individual hormones. When prolactin is observed galactorrhea in the dense granules of acidophilic and somatotropin -producing cells acromegaly ( gigantism, gigantism ) in ACTH -producing adenomas with basophilic cells a Cushing's disease. Pituitary adenomas also occur in MEN 1. The posterior pituitary gland produces antidiuretic hormone ( ADH). In rare cases, thyroid stimulating hormone (TSH ) is produced in excess, which can be formed in accordance with hyperthyroidism.

Hormoninaktive adenomas are discovered later usually due to the later onset of symptoms and are thus larger at diagnosis. By displacing growth of the anterior pituitary may be less supplies, leading to hormone deficiency. Typical are anemia and increased very fine segmentation of the skin in men. The lack of thyroid hormones leads to the symptoms of hypothyroidism with increased fatigue, lack of drive and constipation. The symptoms may pass into the frame of a hypopituitarism. Very rarely, seizures may occur with very large extent.

After clinical diagnosis steer especially the endocrinological symptoms to a pituitary adenoma. The investigation of the Hormonbasalwerte in the blood can be equally groundbreaking, especially the growth hormone and prolactin. Produces an adenoma several hormones, then it is called a mixed tumor.

In conventional X-ray image is an enlargement of the sella turcica can only be identified from a size of about 5 mm. The computed tomography revealed until larger, mostly balloon-shaped pituitary adenomas in a safe place. Therefore, the method of choice is the kontrastvertärkte magnetic resonance imaging, which can detect smaller tumors also a lot. Also, a field measurement should be performed because the tumor can compress the optic nerve.

In pituitary adenomas was observed in 10% of cases cystic swellings ( bubbles) or necrotic (dead ) sections. Calcium deposits are usually associated with prolactin -producing adenomas in conjunction. Microscopically observed monomorphic epithelial cells with a network of capillaries. The nuclei are round to oval and contained a chromatin.

Smaller, asymptomatic, hormoninaktive adenomas ( "null -cell adenomas " ) may constitute up to 20 % of all cases in autopsies.

Therapy

For the treatment of pituitary adenomas are the operational and medical therapy available, which depends entirely on the type of adenoma. In very rare cases of recurrence must be given to radiotherapy.

Therapeutic prolactin -producing adenomas can be treated with the dopamine agonist bromocriptine in particular. Dopamine is a neurotransmitter that allows the hypothalamus normally prevents the pituitary gland produces too much prolactin. The tumors fibrose and may occasionally shrink, upon cessation of treatment they grow partially but again, so then it must be operated on. Even with growth hormone-producing adenomas, a therapeutic trial with bromocriptine is undertaken. Non-response, the alternative is just as surgical.

Alternatively, a surgical resection of the tumor is possible. This process starts before transsphenoidal through the nose, only in larger tumors is carried by a craniotomy, in which the skull must be opened. Regular magnetic resonance tomography (MRT ) are extremely important for monitoring the course of treatment with dopamine agonists and after surgery of the pituitary gland.

It is important to check the hormone levels after treatment accordingly and if necessary to replace a lack of hormone production, especially after radical surgery. Necessary thyroid hormones, gonadotropins and cortisol can be. A central diabetes insipidus Provides a due to ADH deficiency, it must be treated with desmopressin.

Differential diagnoses

Differential diagnosis includes lymphoma, a meningioma or a paraganglioma must be considered in the location of the tumor to a metastatic carcinoma.

Field of view Epithelium Recidivism (medicine) Blastoma Papilloma
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