Hypertrophy is uncommon, but it occurs in cretinism, myxedema, and acromegaly. If the thyroid gland is removed it is thought that the pituitary body sometimes enlarges. The acini may contain a large amount of colloid material.

Hyperemia may occur, and in cases of passive congestion there may be considerable edema. Hemorrhage may take place just before death, and erythrocytes will be found in the connective tissue.

Inflammation is rarely primary, is usually secondary, as a result of extension, and suppuration may occur. The dura covering the gland may become much thickened, and as a result the pituitary body atrophies or undergoes a fibrous change.

Tuberculosis in the form of miliary foci and syphilis in the form of gummata have been observed.

Tumors

Sarcomata, round-cell or spindle-cell, are sometimes found. They develop apparently from the capsule of the gland and destroy the substance. They seldom infiltrate the surrounding tissue and do not give metastases.

Adenoma causes a general enlargement and is the growth most commonly found associated with acromegaly. It consists of long, tortuous tubes, and causes atrophy of the posterior or nervous lobe.

Teratoid growths have been described.

Cysts are generally the result of retention of the colloid material. The epithelial cells disappear and the follicles distend. The cysts may grow to the size of a hen's egg.