The disease which is often also associated with gigantism, is difficult to diagnose in the early stages and is frequently missed for many years, until changes in external features, especially of the face, become noticeable with the median time from the development of initial symptoms to diagnosis being twelve years. Cushings syndrome is a hormonal disorder that causes hypercortisolism, which is elevated levels of cortisol in the blood. Cushings disease (CD) is the most frequent cause of Cushings syndrome, responsible for approximately 70% of cases. CD results when a pituitary adenoma causes excessive secretion of adrenocorticotropic hormone (ACTH) that stimulates the adrenal glands to produce excessive amounts of cortisol.Cushings disease may cause fatigue, weight gain, fatty deposits around the abdomen and lower back (truncal obesity) and face ("moon face"), stretch marks (striae) on the skin of the abdomen, thighs, breasts, and arms, hypertension, glucose intolerance, and various infections. In women, it may cause excessive growth of facial hair (hirsutism) and in men erectile dysfunction. Psychiatric manifestations may include depression, anxiety, easy irritability, and emotional instability. It may also result in various cognitive difficulties.Hyperpituitarism is a disease of the anterior lobe of the pituitary gland which is usually caused by a functional pituitary adenoma and results in hypersecretion of adenohypophyseal hormones such as growth hormone; prolactin; thyrotropin; luteinizing hormone; follicle-stimulating hormone; and adrenocorticotropic hormone.
Anatomically pituitary tumors are classified by their size based on radiological findings; either microadenomas (less than <10 mm) or macroadenomas (equal or greater than ≥10 mm).Classification based on radioanatomical findings places adenomas into 1 of 4 grades (I–IV):Stage I: microadenomas (<1 cm) without sella expansion.Stage II:  macroadenomas (≥1 cm) and may extend above the sella.Stage III:  macroadenomas with enlargement and invasion of the floor or suprasellar extension.Stage IV: destruction of the sella.Histological classification utilizes an immunohistological characterization of the tumors in terms of their hormone production. Historically they were classed as either basophilic, acidophilic, or chromophobic on the basis of whether or not they took up the tinctorial stains hematoxylin and eosin. This classification has fallen into disuse, in favor of a classification based on what type of hormone is secreted by the tumor. Approximately 20–25% of adenomas do not secrete any readily identifiable active hormones (non-functioning tumors) yet they are still sometimes referred to as chromophobic. Functional classification is based upon the tumors endocrine activity as determined by serum hormone levels and pituitary tissue cellular hormone secretion detected via immunohistochemical staining. The "Percentage of hormone production cases" values are the fractions of adenomas producing each related hormone of each tumor type as compared to all cases of pituitary tumors, and does not directly correlate to the percentages of each tumor type because of smaller or greater incidences of absence of secretion of the expected hormone.