DR.GEHAN MOHAMED

Pituitary tumors

What is a Pituitary tumor?

The pituitary gland is a pea sized endocrine gland located at the base of the brain.

A pituitary Tumor is caused by an abnormal growth in the pituitary gland.

Most of pituitary tumors are benign called adenoma ,but pituitary carcinoma is rare.

Incidence of pituitary tumors

pituitary tumors represent 8.4% of all primary brain tumors.

Can occur to people of all ages, most frequent in children and older adults.

In ages 20-34, pituitary tumors are most common followed by meningioma tumors.

to differentiate pituitary adenoma from pituitary carcinoma , the latter is characterized by tumor cells reaching cerebrospinal fluid or distant metastases.

Effects of pituitary tumors

A pituitary tumor can cause trouble in two ways:

1- physical effect :When a pituitary tumor is relatively large — measuring close to 1/2 inch (1 centimeter) or more in diameter — it can exert physical pressure on the rest of the normal pituitary gland so The hormone releasing cells of the pituitary gland can be damaged also nearby structures to the pituitary can be compressed as the optic nerve has serious damage you can go blind.2-biochemical effect : Sometimes pituitary tumors can cause excessive production of hormones . Other times, pituitary tumors can restrict your pituitary gland, causing it to produce lower levels of hormones.

Classification of pituitary adenoma according to size :

Pituitary adenomas have separate names based on their size. A microadenoma is less than 1 centimeter in

diameter A macroadenoma is larger than 1

centimeter in size

Classification of pituitary adenoma according to behavior

1- typical pituitary adenoma (classic type ).

2- invasive pituitary adenoma: if the adenoma invade surrounding structures

3- atypical pituitary adenoma : characterized by P53 tumor suppressor gene mutation and immunohistochemical positivity for proliferation markers as Ki67

Classification of pituitary adenoma according to staining characteristics

They can be classified on the basis of staining characteristics into :

1- chromophobic cell tumor2- chromophilic cell tumors : which can be further subdivided using hematoxylin and eosin stains into 1- acidophil cell tumor : secreting growth hormone,prolactin .

2- basophil cell tumor : secreting (ACTH,TSH,FSH,LH)

Diagnosis of pituitary tumors

1- clinical picture

2- investigations

1- Clinical picture of pituitary tumor

HeadacheNausea and vomitingLethargy: lack of energyProblems with the sense of smellVisual changes such as

-Double vision-Drooping eyelids-Visual field loss

Symptoms related to hormone level changes ( either increase or decrease) secondary to pituitary tumors

Symptoms related to hormone level changes ( either increase or decrease) secondary to pituitary tumors

1- Prolactin: Overproduction of prolactin from a pituitary tumor (prolactinoma) can cause a decrease in normal levels of sex hormones — estrogen in women and testosterone in men.

- Excessive prolactin in the blood (hyperprolactinemia) can affect men and women differently. In women, prolactinoma may cause irregular menstrual periods (oligomenorrhea), lack of menstrual periods (amenorrhea) and milky discharge from the breasts (galactorrhea).

-

In men, a prolactin-producing tumor may cause male hypogonadism, which may involve signs and symptoms such as enlarged breasts (gynecomastia), erectile dysfunction (ED) or impotence, infertility, decrease in body hair, and loss of interest in sexual activity.

2- Adrenocorticotropic hormone: 1- Overproduction: These pituitary tumors produce the hormone adrenocorticotropin, which stimulates your adrenal glands to make the hormone cortisol. When your adrenal glands produce too much cortisol, a condition called Cushing's syndrome occurs. Signs and symptoms of Cushing's syndrome may include weight gain around midsection and upper back, exaggerated facial roundness, a characteristic hump on the upper part of your back, high blood pressure, muscle weakness, bruising, stretch marks and thinning of your skin.

2- adrenocorticotrophic hormone deficiency:deficiency limited to glucocorticoids and adrenal androgens , but mineralocorticoid not decreased as it dependent on the angiotensin-renin axis) but in case of primary adrenal insufficiency there will be deficency in all (mineralocorticoid,glucocorticoid,sex hormones ).

Initially, symptoms nonspecific (eg, weight loss, lack of energy, malaise); severe adrenal insufficiency may present as a medical emergency

3-Growth hormone 1- overproduction: These tumors produce excess growth hormone. The effects from excess growth hormone in adults (acromegaly) may include coarsened facial features, enlarged hands and feet, excess sweating, high blood pressure and heart problems. Accelerated and excessive growth (gigantism) may occur in children.

2- Growth hormone deficiency- Adults - Increased rate of cardiovascular disease, obesity, reduced muscle strength and exercise capacity, and increased cholesterol- Infants - Hypoglycemia- Children - Decreased height and growth rate (pituitary dwarfism)

Gigantism due to increase growth hormone

Acromegaly

Acidophil cellTumor secreting growth hormone after puberty lead to acromegaly:

Enlargement, thickening, and broadening of bones

Particularly extremities of the body

Acromegaly :

4- Thyroid-stimulating hormone (TSH) 1- overproduction: When a pituitary tumor overproduces thyroid-stimulating hormone, your thyroid gland makes too much of the hormone thyroxine. This is a rare cause of hyperthyroidism, or overactive thyroid disease. Hyperthyroidism can accelerate your body's metabolism, causing sudden weight loss, a rapid or irregular heartbeat, and nervousness or irritability. 2-Thyrotropin deficiency : cause cretnism in infants or myxedema in adults which characterized by Malaise, weight gain, lack of energy, cold intolerance, and constipation

5- Gonadotrophin deficiency (FSH,LH) - Men - Diminished libido and impotence; testes shrink in size, but spermatogenesis generally preserved - Women - Diminished libido and dyspareunia; breast atrophy in chronic deficiency - Children - Delayed or frank absence of puberty - Adolescent girls - Present similarly to adult women

Clinical effects due to Hormonal deficiencies

6- Panhypopituitarism - Refers to deficiency of several anterior pituitary hormones; may occur in a slowly progressive fashion.

2- investigations

Blood and urine tests. Tests of your blood and urine samples can determine whether you have an overproduction or deficiency of hormones (growth hormone,prolactin,TSH,ACTH).

Brain imaging. A computerized tomography (CT) or magnetic resonance imaging (MRI) scan of your brain can help your doctor judge the location and size of a pituitary tumor.

Vision testing. Such tests can determine if growth of a pituitary tumor has impaired your sight or peripheral vision.

Normal pituitary versus pituitary adenoma. Note the delicate acinar pattern of a normal pituitary gland (left), in contrast with

disruption of the normal reticulin network in adenoma (right) (Wilder's reticulin stain

Histology of a normal anterior pituitary gland. The gland is formed of multiple cell types, including basophilic, eosinophilic,

and chromophobic cells (hematoxylin-eosin stain).

Pituitary adenoma is characterized by a monomorphic expansion of usually one cell type with lack of reticulin network among neoplastic cells. The growth pattern can be diffuse, trabecular (as in this case),

pseudo-acinar or pseudo-papillary.

Immunohistochemical staining of pituitary adenoma

Positive staining for cytokeratin (CK) in tumor cells.

To determine if the pituitary adenoma is functioning or not ,also to detect type of hormone secreted we can use antibodies to detect pituitary hormones (ACTH, FSH, LH, TSH, GH, PRL).

Treatment for pituitary tumors involves :

1- medications to correct hormone production that is too high or too low.

2- Surgery especially if the tumor is pressing on the optic nerves. - tumor Can be removed through the nose or sinuses. - If it doesn’t work through the nose or sinuses it will have to be removed through the skull. 3- Radiation therapy can be used to shrink the tumor, It can be used for people who cannot be put through surgery.

Surgical treatment of pituitary adenoma