Pituitary adenomas are one of the most frequent intracranial tumors and occur with a prevalence of approximately 1:1000 in the developed world. The Pituitary gland (P) is located in the Sella turcica (S) at the base of the skull. It measures less than 10 millimeters in diameter. Its importance can be judged by the fact that it is known as the ‘master’ gland of the endocrine ‘orchestra’ in view of the control it exerts on majority of endocrine glands in the body.

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The Pituitary gland is an amalgam of two tissues consisting of the Anterior and Posterior components which are distinctly different in structure, reflecting their differing embryological origins.

Like most tumors the exact cause of pituitary adenomas is not known. In the majority of cases these may occur as isolated tumors or as components of a syndrome like Multiple Endocrine Neoplasia type 1 and Carney complex. Few genetic predictors of Pituitary adenoma development exist.

neoplasms more than 10 mm that may be contained within the sella turcica but often infiltrate into the superior, inferior and/or lateral extrasellar space. Furthermore, pituitary neoplasms may be classified as functional or nonfunctional, where functional neoplasms present with clinical symptoms specific to increased hormonal secretion and activity. Nonfunctional pituitary adenomas commonly present due to mass effect or are identified incidentally on autopsy. Therefore, almost all NFAs are large extrasellar macroadenomas.

The NFAs represent a group of adenomas that include the Thyroid Stimulating Hormone (TSH), Follicle Stimulating Hormone (FSH), and Luteinising Hormone (LH), the Null cell adenomas and Oncocytoma. Clinically NFAs, mostly derived from gonadotroph cells, are often large and cause symptoms of mass effects such as visual disturbance, cranial nerve palsies, or headache.

Like most tumors the exact cause of pituitary adenomas is not known. In the majority of cases these may occur as isolated tumors or as components of a syndrome like Multiple Endocrine Neoplasia type 1 and Carney complex. Few genetic predictors of Pituitary adenoma development exist.

A clinical condition of Familial Isolated Pituitary Adenomas (FIPA) has been described, which encompasses the familial occurrence of isolated pituitary adenomas outside of the setting of syndromic conditions like Multiple Endocrine Neoplasia Type 1 and Carney complex. FIPA families comprise approximately 2% of pituitary adenomas. The aryl hydrocarbon receptor interacting protein (AIP) gene has been implicated in 20% of FIPA families.

Most GH secreting Pituitary adenomas usually form from a genetic mutation in one a single, pituitary cell called a ‘Corticotropic’ cell. This mutation causes uncontrolled growth and reproduction of these cells.

Clinically NFAs have a prevalence of 7090 cases/million population and comprise 15% of all pituitary adenomas.

Diagnosis of NFAs is made based on:

  1. The main presenting symptomsof NFAs are visual defects (65%) and headache (40%) and the most frequent pituitary deficit is hypogonadism (45%), since almost all tumors are macroadenomas (96.5%).
  2. Hormone profile: Hypopituitarism in 40% of cases.

Clinically NFAs have a prevalence of 7090 cases/million population and comprise 15% of all pituitary adenomas. Diagnosis of NFAs is made based on:

  1. The main presenting symptomsof NFAs are visual defects (65%) and headache (40%) and the most frequent pituitary deficit is hypogonadism (45%), since almost all tumors are macroadenomas (96.5%).
  2. Hormone profile: Hypopituitarism in 40% of cases.
  3. Magnetic Resonance Imaging of Brain including Sella turcica: The pituitary adenoma responsible for Cushing’s disease is a macroadenoma in more than 95% of cases. NFAs more than 40 mm in size are called ‘Giant’ by nomenclature.
Pituitary-adenoma--NFA-MR-sag-01 Pituitary-adenoma--NFA-MR-cor-01

The goals of treatment in Nonfunctioning adenomas (NFA) are:

  1. To decrease the size of a pituitary adenoma (if present) thereby relieving pressure on the surrounding tissue,
  2. To maintain normal pituitary function, and reverse or improve associated symptom.

The primary goal of surgery for NFA is decompression of neural structures, especially the optic chiasm, cavernous sinus and subfrontal brain.

Endocrine-inactive Pituitary adenomas are the most common surgically treated pituitary tumor. Because they are not associated with hormonal hypersecretion, with the occasional exception of hyperprolactinemia secondary to stalk effect, these tumors are typically diagnosed as macroadenomas. NFAs are comprised of several pathologically different types of tumours, some of which are potentially hormone producing, but some defects in hormone secretion or production of biologically inactive or insufficient amount of hormone may be the culprit in the lack of evidence of rising serum hormone levels. Given that no effective pharmacotherapy exists for these tumors, transsphenoidal removal is considered the optimal treatment.

Transsphenoidal approach is safe and effective procedure even in large or giant pituitary adenomas, because it allows rapid and appropriate decompression of the optic nerves and chiasm with low morbidity rates. Transcranial approaches were indicated only in irregular shaped adenomas or eccentric extensions that could not be reached through the transsphenoidal route (See in pictures below).

Pituitary-adenoma--Transcranial-approach-01 Pituitary-adenoma--Transcranial-approach-02

Surgery is the first choice treatment (98% of patients) and total debulking is achieved in only one-third of patients in NFAs. In the case of Giant pituitary tumor, in general, total removal is very rare, and they progress frequently.