Treatment of prolactinomas (pituitary adenomas that secrete prolactin) with dopamine agonist drugs, as well as withdrawal of such treatment, has been reported to precipitate apoplexy.Hemorrhage from a Rathkes cleft cyst, a remnant of Rathkes pouch that normally regresses after embryological development, may cause symptoms that are indistinguishable from pituitary apoplexy. Pituitary apoplexy is regarded by some as distinct from Sheehans syndrome, where the pituitary undergoes infarction as a result of prolonged very low blood pressure, particularly when caused by bleeding after childbirth. This condition usually occurs in the absence of a tumor. Others regard Sheehans syndrome as a form of pituitary apoplexy. Mechanism
The pituitary gland is located in a recess in the skull base known as the sella turcica ("Turkish saddle", after its shape). It is attached to the hypothalamus, a part of the brain, by a stalk that also contains the blood vessels that supply the gland. It is unclear why pituitary tumors are five times more likely to bleed than other tumors in the brain. There are various proposed mechanisms by which a tumor can increase the risk of either infarction (insufficient blood supply leading to tissue dysfunction) or hemorrhage. The pituitary gland normally derives its blood supply from vessels that pass through the hypothalamus, but tumors develop a blood supply from the nearby inferior hypophyseal artery that generates a higher blood pressure, possibly accounting for the risk of bleeding.
Psoriasis and psoriatic arthritis are interrelated heritable diseases, occurring with greater heritable frequency than rheumatoid arthritis, primary Sjögren syndrome and thyroid disease. Psoriasis affects 2–3% of the Caucasian population, and psoriatic arthritis affects up to 30% of those. Arthritis mutilans presents in about 5–16% of psoriatic arthritis cases, involves osteolysis of the DIP and PIP joints, and can include bone edema, bone erosions, and new bone growth. Most often psoriatic arthritis is seronegative for rheumatoid factor (occurring in only about 13% of cases), and has genetic risk factor overlap with ankylosing spondylitis with HLA-B27, IL-23R77, and IL-1, however, as of 2016, immunopathogenesis is unclear. Diagnosis
Enthesitis can assist in differentiating arthritis mutilans parent condition psoriatic arthritis from rheumatoid arthritis and osteoarthritis, with evidence in plain radiographs (x-rays) and MRI as periostitis, new bone formation, and bone erosions. Dactylitis, spondylitis and sacroiliitis are common with the parent condition psoriatic arthritis, but are not in rheumatoid arthritis. MRI bone edema scores are high in arthritis mutilans and correlate with radiographic measures of joint damage, although they may not correlate with disease activity. A source of significant pain, bone marrow edema (or lesions, using newer terminology), can be detected on MRI or with ultrasonography by signals of excessive water in bone marrow. Specifically, bone marrow edema can be detected within bone on T1-weighted images as poorly defined areas of low signal, with a high signal on T2-weighted fat-suppressed images.