Pituitary gland

an endocrine gland, also termed the hypophysis, which is attached to the hypothalamus by a stalk. It produces and secretes hormones regulating such events as growth, thyroid function and maturation of gonads. Musculoskeletal effects occur with either hyperfunction or hypofunction of the pituitary. Also, see pituitary gland.

2. Pathology

Acromegaly and gigantism result from hyperpituitarism or excess secretion of pituitary hormones, especially growth hormone, which leads to reactivation of endochondral bone formation. Characteristic radiographic findings are seen, including increased soft tissue thickness and bone overgrowth. Joint abnormalities result from proliferation of chondrocytes in articular cartilage. On radiographs, joint space narrowing, bone sclerosis, cyst formation and osteophytosis are eventually noted.

In hypopituitarism, decrease or ablation of pituitary function occurs from various causes, including surgery, infections, irradiation, postpartum necrosis and chromophobe adenoma. In some cases hypopituitarism is inherited. Delayed appearance and growth of ossification centres as well as in delay in their fusion and disappearance is characteristic. The growth plate remains open and its metaphyseal side is "closed off" as bone abuts on the cartilaginous tissue. Immature body proportions and facial features, abnormal distribution of fat, and delay in eruption of secondary teeth are among the features of hypopituitarism. In patients with hypopituitarism, treatment with human growth hormone results in an increase in skeletal maturation paralleling the increase in chronological age and an increase in cortical thickness. In rare instances, slipped capital femoral epiphysis may occur before or during growth hormone therapy in patients with pituitary dysfunction.

DR