Pituitary carcinoma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Masoud Bitarafan, M.D[[2]]

• pituitary carcinoma was first discovered by Pierre Marie, a French neurologist (Salpetriere Hospital, Paris) in 1886 following his studying in two patients with clinical findings of what he termed acromegaly and postulated that the pituitary gland was involved in the pathogenesis.^[1]
• Earlier, A DNA examination from the teeth of an Irish patient with gigantism (7 ft, 7 in in height), who lived from 1761 to 1783, revealed the same mutation in the AIP gene, present in 4 families with pituitary tumors from Northern Ireland. The skull of this patient was actually examined later by Harvey Cushing and Sir Arthur Keith in 1909 and found to have an enlarged pituitary fossa, reflecting the enlarged pituatary gland. Recent technologic advances in genetics provide valuable insight into the disease.

• Pituitary carcinoma may be classified according to the type of cells involved into following subtypes:^[2][3]

• Corticotroph carcinoma
• Prolactin-secreting carcinomas
• Gonadotroph carcinomas
• Growth hormone–secreting carcinoma

• Several possible causes have been proposed for pathogenesis of Pituitary carcinoma.^[4]The pathogenesis of pituitary carcinoma is characterized by :

1. consequence of pervious irradiation in a treatment of a pituitary carcinoma
2. microscopic tumor seeding from a pervious Pituitary surgery
3. malignant progression of a Pituitary carcinoma
4. denovo carcinoma

• The [gene name] gene/Mutation in [gene name] has been associated with the development of [disease name], involving the [molecular pathway] pathway.
• On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of pituitary carcinoma
• On microscopic histopathological analysis, hypochromatasia, nuclear pleomorphism with prominent nucleoli,and mitotic activity are characteristic findings of pituitary carcinoma^[5][6]

• Nelson syndrome^[5]
• Multiple endocrine neoplasia type 1 (MEN1)
• Familial acromegaly.
• Carney complex.

• Differential diagnosis of pituitary carcinoma from pituitary adenoma is important since both usually present with similar features .

• The prevalence of pituitary carcinoma is very rare as it accounts for 0.1-0.2% of all pituitary tumors and approximately 4616 individuals worldwide and 207 in US.^[5][7]

• Pituitary carcinoma can present at any age however, patients with preexisting pituitary adenoma develop pituitary carcinoma in the third to fifth decade of life.^[8]

• Pituitary carcinoma affects men and women equally.^[5]

American Blacks have higher incidence rates for pituitary tumors compared with other ethnic groups.^[9]The study of Heshmat et al. supports this possibility with the finding that African Blacks have higher relative proportions of pituitary tumors compared to American Whites (although still not as high as American Blacks)^[9]

• Pituitary tumors have not been linked with any known outside risk factors.
• Patients with the folllowing hereditary syndroms are at higher risk of the developing pituitary tumors^[10] :

1. Multiple endocrine neoplasia type 1 (MEN1). Families with MEN1 have an increased risk of pituitary gland tumors.
2. Carney complex. Like MEN1, the Carney complex is a rare genetic condition that can increase the risk of a pituitary gland tumor.
3. Familial acromegaly. Acromegaly is a condition in adults that is caused by too much growth hormone. Familial acromegaly can occur as part of MEN1, described above, or alone within a family.

• The majority of patients with pituitary carcinoma remain asymptomatic. The average survival of afflicted patients span from a few months to 18 years depending upon the subtype.^[5]
• Common complications of pituitary tumors include blindness,diabetes insipidus, permanent hormone deficiency, and pituitary apoplexy.^[11]

• At present, the diagnosis of pituitary carcinoma depends on the demonstration of metastatic spread. There are no morphologic criteria to distinguish locally aggressive, or even markedly atypical, adenomas from carcinomas when the tumor is confined to the sella. Standard morphologic features associated with carcinoma are listed below:^[12]

1. hypercellularity
2. nuclear and cellular pleomorphism
3. increased mitotic activity
4. necrosis
5. dural/osseous invasion

A pituitary tumor causes symptoms thrgouh different ways:^[13]

• Most of the symptoms of pituitary carcinomas are associated with high production of hormons:

1. Growth hormone. The symptoms depend on a patient’s age. In children, before the bone plates have closed, increased growth can cause gigantism, which is excessive body size and height. In adults, increased growth hormone causes acromegaly, a syndrome that includes excessive growth of soft tissues and bones, high blood sugar, high blood pressure, heart disease, sleep apnea, increased snoring, carpal tunnel syndrome, and pain, including headaches
2. Thyroid stimulating hormone (TSH). Too much TSH causes increased production of thyroid hormone. This can lead to nervousness and irritability, fast heart rate and high blood pressure, heart disease, increased sweating, thin skin, and weight loss.
3. Prolactin. Too much prolactin, a hormone that stimulates lactation and the secretion of progesterone, causes inappropriate secretion of breast milk, even in men. It can also cause osteoporosis, which is weakening of the bones; loss of sex drive; infertility; irregular menstrual cycles; and the inability to have an erection.
4. Adrenocorticotropic hormone (ACTH). Too much of this hormone causes weight gain, particularly in the body’s trunk. It can also cause high blood pressure, high blood sugar, brittle bones, emotional changes, stretch marks on the skin, and easy bruising.
5. Gonadotropins (FSH and LH). Distruption in FSH and LH levels is associated with infertility and irregular menstrual cycles in women.

• Pituitary carcinomas by pressing the adjacent structures cause too little production of 1 or more hormones:

1. Growth hormone. Not enough growth hormone causes late growth in children, poor muscle strength, irritability, weakening of bone strength, and an overall unwell feeling.
2. TSH. Low TSH causes fatigue, low energy, sensitivity to cold temperatures, constipation, and weight gain.
3. Prolactin. Too little prolactin causes an inability to breastfeed after a woman gives birth to a baby.
4. ACTH. Too little of this hormone causes fatigue and low energy, low blood pressure, low blood sugar, and upset stomach.
5. Gonadotropins. Low levels of gonadotropins cause infertility, decrease in sex drive, an inability to have an erection, and irregular menstrual cycles.

• Pituitary carcinomas is associated with loss of part or all of a person’s sight, or double vision by pressing on the optic nerves.

• Patients with pituitary carcinoma usually appear [general appearance].
• Physical examination may be remarkable for:

• [finding 1]

• There are no specific laboratory findings associated with pituitary carcinoma

• A [positive/negative] [test name] is diagnostic of pituitary carcinoma
• An [elevated/reduced] concentration of [serum/blood/urinary/CSF/other] [lab test] is diagnostic of pituitary carcinoma
• Positive stain of ki67 and p53 can be helpful in diagnosis of pituitary carcinoma.^[6]

• CT and particularly MR scanning, exert high sensitivity in detecting pituitary pathology; in addition, these techniques can be used to demonstrate disease progression elsewhere and thus the presence of metastases even when pituitary pathology has remained stable .^[14]

Histological and immunohistochemical parameters are commonly employed to predict the biological behavior of pituitary tumors:
^[14]

Pituitary carcinomas are generally associated with a poor prognosis despite administration of maximal multimodal therapies . Patients with systemic metastases succumb in 12 months, while those with metastases confined to the central nervous system live longer with an average of 2.6 yr.^[8]

Treatment options for Pituitary carcinoma include^[15]:

• surgery
• external radiotherapy
• medical treatment
• peptide receptor radionuclide therapy.

Current therapeutic modalities are mainly palliative, and once metastases develop, the prognosis of these tumors is relatively poor.

• Medicines are used to manage hormone levels in functional pituitary carcinomas.
• These are the same drugs used to treat pituitary adenomas, but higher doses and combinations of drugs may be needed.^[16]
• Some medicine which is used are listed below:^[17]

1. drugs for prolactin-secreting tumors:dopamine agonists such as cabergoline and bromocriptine
2. drugs for growth hormone- secretings timors:somatostatin analogs such as octreotide or lanreotide.
3. drugs for corticotropin-secreting tumors:somatostatin analog such as pasireotide or cortisol receptor blocker such as mifepristone.

• Surgery and radiation therapy are the mainstay treatment for pituitary carcinoma.
• . They may decrease tumor size, slow tumor growth, and help prevent or relieve symptoms. In case of recurrence, repeated surgery is considered.^[16] Pituitary surgeries are done in the following ways:^[18]

1. Transsphenoidal surgery
2. craniotomy(for larger or more complicated pituitary tumors.

• Radiation therapy is a second approach after surgery. Radiation therapy is considered if some of a pituitary tumor remains or comes back after surgery, or if the tumor causes symptoms that aren’t controlled with medicines.^[19]
• There are some Newer techniques help lower the risks of radiation therapy which are listed below:^[19]

1. Intensity modulated radiation therapy (IMRT)
2. Stereotactic radiosurgery/stereotactic radiation therapy
3. Proton beam radiation therapy

• A number of different chemotherapy protocols have been used; however, the response to treatments is not usually successful:^[4]

1. carmustine
2. hydroxyurea
3. 5-fluorouracil
4. others

• There have been no outside risk factors reported for Pituitary tumors. Therefore, there is no known way to prevent these tumors at this time.^[20]

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