1937 American doctor McCune and al-bright respectively report a disease with polyostotic fibrous dysplasia, non protruding skin brown pigmen
1937 American doctor McCune and al-bright respectively report a disease with polyostotic fibrous dysplasia, non protruding skin brown pigmentation and precocious characteristics of the three, later named McCune-Albright syndrome, is a rare clinical disease.
McCune-Albright Syndrome (MAS) is also referred to as multiple fibrous dysplasia and precocious puberty syndrome, which is characterized by skin coffee spot, precocious puberty and multiple fibrous dysplasia of bone. Clinical is relatively rare, the disease is sporadic, the incidence of women is two times that of men. The classification of diseases, diseases in Department of Endocrinology Department of orthopedics 1937 American doctor McCune and al-bright reported a disease with polyostotic fibrous dysplasia, non protruding skin brown pigmentation and precocious characteristics of the three, later named McCune-Albright syndrome, is a rare clinical disease. The main manifestations were three types of symptoms, such as endocrine dysfunction, fibrous dysplasia of the skin, and color of the skin. Its endocrine dysfunction can be manifested as precocious puberty, hyperthyroidism, Cushing syndrome, prolactin, growth hormone secretion, cortisol, and so on, of which the most common precocious puberty. The disease was distributed, all kinds of ethnic groups have patients, the incidence of women is higher than men. Because of its diverse clinical manifestations, it is easy to confuse with various diseases. The pathological basis of symptoms and signs of clinical manifestations of multiple fibrous dysplasia of bone damage is MAS bone fibrous dysplasia of bone progenitor cells can mature into pre osteoblasts, bone damage in thin trabecular widely absorbed, there are signs of spider web like, like a spider net internal bone with bone cartilage island. Thin cortex bone, affected by heavy break easily under pressure. Endocrine abnormalities, endocrine abnormalities, the most prominent symptoms of precocious puberty, performance for the early development of secondary sexual characteristics, menstrual cramps, early sexual changes and vaginal bleeding when the time of ovulation. Gas sexual precocity and other diseases of premature infants are different in female children with irregular vaginal bleeding symptoms, often due to unilateral ovarian cyst are caused by the secretion of estrogen, has nothing to do with gonadotropin. Estrogen promotes breast enlargement, growth acceleration, and serum gonadotropin is not high, GnRH stimulation test LH reaction is low. Ovarian cysts and irregular vaginal bleeding can persist into adolescence. Male patients with precocious puberty is rare, if the occurrence of precocious puberty, the development of the external genitalia, serum testosterone levels up to puberty. The main clinical manifestations of McCune-Albright syndrome are as follows: one or more endocrine gland hyperplasia or adenoma caused by autonomic hyperfunction. The most common is the emergence of independent functional ovarian follicular cyst, and sex hormone activity, but no gonadotropic activity, no ovulation, resulting in non GnRH dependent sexual precocity, manifested as secondary sexual characteristics, menstrual cramps, early development of early sex change and vaginal bleeding when the time of ovulation. Early epiphyseal maturity. The level of serum estrogen was increased and the level of gonadotropin was low, and the fluctuation of estrogen level was consistent with the change of ovarian function. GnRH stimulation test showed that the LH reaction was low. But the long-term high sex hormone status can induce precocious puberty. Other endocrine glands lesions may also cause hyperthyroidism, hypercortisolism, gigantism, acromegaly or hyperprolactinemia. Multiple fibrous dysplasia of bone. In craniofacial bone and bone, a lateralization asymmetry, with facial asymmetry, often manifested as local pain and skeletal deformities, was prone to pathological fracture, reduce adult. Sometimes the bone proliferation can cause local compression symptoms, such as cranial nerve compression of adjacent bone lesions cause blindness, deafness, compression of the pituitary gland caused by endocrine dysfunction. Irregular edge of the skin coffee pigment spots. It is not always present at birth, and often occurs on the same side of the lesion, rarely beyond the midline. The severity of clinical symptoms was related to the occurrence of the mutation in the early stage of the embryo. A wide range of lesions can occur in the early stage of the mutation, which may lead to a typical triad. In the later stage of the mutation, the lesion range is small, even isolated. Etiology and pathological changes 1, the etiology of the disease is based on the genetic basis of the formation of guanine nucleotide binding protein (G protein) alpha subunit (Gs) gene mutation in the process of embryo formation. The common mutation is Gs encoding alpha subunit gene is located on the long arm of chromosome 20 in exon 8 of the Arg 201 His or Arg 201Cys missense mutation, mutation makes lesions within the cell matrix of the central 3, 522 AMP level increased significantly, resulting in cAMP dependent receptors (such as ACTH, TSH, FSH, LH receptor) be spontaneously activated, in endocrine tissues self-discipline too much of the hormone secretion or hormone resistance process. Only part of the somatic mutation can survive, or abortion. 2, the pathological changes and cell membrane receptor G protein coupling by alpha, beta, Gamma 3 subunit polypeptide. It can be divided into two types according to their biological functions: Gi (inhibitory) (Gs) and. In the basal state, the Gs protein is bound to two guanosine phosphate. When combined with hormone and membrane receptor, Gs protein is activated, beta, gamma subunit dissociation was down, forming Gs three alpha 2 guanosine monophosphate (GTP), Gs alpha 2GTP reactivation of adenylate cyclase enzyme in plasma membrane (AC), adenosine triphosphate (ATP) and catalytic generation of cyclic adenosine monophosphate (cAMP), cAMP as the second messenger, via activation of protein kinase A, directly or indirectly, so that a variety of protein phosphorylation, effects of biologically active hormone activated receptor. The Gs alpha subunit gene in ovarian cell mutation, ovarian sustained activation in the state, had the self-discipline of the excessive secretion of estrogen and formation of luteinized theca cells have the function of non gonadotropin releasing hormone (GnRH) dependent precocious performance. In the activation of Gs can promote bone involvement in the proliferation of osteoblasts, but bone tissue differentiation, osteoblast maturation disorder, bone surface of osteoblasts decreased, osteocalcin level low, bone mineralization, and bone matrix in immature fibrous interstitial cell proliferation and disorderly deposition, resulting in a fibrous bone many dysplasia. Mutations in the skin Gs alpha subunit gene to increase melanin secretion of melanin cells, the emergence of skin coffee spots. The disease is self limited diagnostic tendency, the following measures can improve the clinical symptoms, including: medical treatment of 1 bone lesions (1) calcitonin: calcitonin 50 ~ 100U or elcitonin 40U the next day or 1 week 2, intramuscular injection, some people think that the drug caused by limited swelling and bone fracture bone deformities caused by stimulation of nerve endings of pain has obvious analgesic effect, no obvious side effects, because of the expensive price effects of long-term medication. (2) the preparation of phosphate: efficacy of different reports, commonly used are: EHDP (disodiumedetate): 20mg/kg per day, oral treatment for 6 months to 1 years. The pamidronate (pamidronate):60mg/d, intravenous drip for 3 days, repeated 1 times every 6 months. The patient had no spontaneous fractures during treatment, in the treatment of 2 ~ 3 after treatment of bone pain and gait abnormalities disappeared, limb length did not change, serum ALP, urinary hydroxyproline decreased, but has not yet been cured and damaged bone scintigraphy confirmed by radiology. The use of the above two drugs has not seen significant side effects (may be associated with too few cases observed), the mechanism of action is not yet clear. 2 surgical treatment of skeletal deformities may be feasible for MAS patients with severe limb deformities. Curettage of bone, bone graft and internal fixation, postoperative recurrence. If the disease is growing rapidly, to be alert for malignant bone fibrosarcoma, followed by osteosarcoma, not time for radiotherapy, so as not to cause malignant transformation. 3 the treatment of precocious puberty () Jing (MPV):5 ~ 10mg/d, can inhibit the secretion of FSH, LH, so that the breast retraction, menstrual stop, or make the Yin and testicular narrowing, pubic hair reduction, curative effect. A minority of patients with nausea, vomiting, fatigue, drowsiness and other side effects, liver, renal toxicity. (2) megestrol acetate (danazol, danacrin, danazol) can inhibit the secretion of gonadotropin climax, did not inhibit the normal in vivo FSH, LH basic level, effect as above, the amount used 50mg/ times, 1 ~ 2 /d or adjusted dose. Side effects of elevated liver transaminase, long-term application of the need to regularly check the liver function, liver dysfunction are not large doses. (3) medroxyprogesterone acetate (depoprovera): intramuscular injection every 100 ~ 200mg, 2 ~ 3, every week 1, effectiveness is similar to MPA. (4): ketoconazole can inhibit adrenal and gonadal steroidogenesis. Recently from the Maryland Medical Center Syed and chalew reported that they used was 200mg, 1 years after the 3 /d treatment of 2 cases of MAS female patients with precocious puberty, precocious puberty was checked. Side effects of skin itching, skin rash, but does not affect the use of abnormal liver function can be restored after withdrawal. (5) testosterone lactone: can inhibit the secretion of estrogen, promote breast maturation of girls. Bone growth and bone maturation. The effect of non gonadotropin dependent precocious puberty. The dosage was 20 ~ 40mg/ (kg? D). (6) Tamocy Finn (tamoxifen): is currently considered to be the best anti gonadotropin dependent precocious puberty drugs, which can compete with estrogen estrogen receptors, estrogen depletion. After this treatment, the development of youth slowed down, linear growth decreased, during the onset of puberty, given GnRH analogues treatment, growth rate and bone maturation remained stable. Dosage of 10 ~ 20mg, the 2 /d. Treatment and prognosis: the treatment of McCune-Albright syndrome is symptomatic treatment, there is no effective cure method. Precocious children and parents can cause psychological burden, and may lead to early epiphyseal closure of final height. The function of the control of other endocrine glands is directly affecting the survival of children. Abnormal proliferation of bone fibers can cause bone deformity, dysfunction or fracture. Treatment includes: treatment of endocrine gland hyperfunction: the main application of aromatase inhibitors (i.e., testosterone, progesterone and medroxyprogesterone acetate) treatment, the feedback inhibition produced in the pituitary gonadotropin, the sex hormone, sex subsided; but it cannot control bone growth too fast, can not prevent short stature, and long term use can inhibit the secretion of pituitary ACTH, these drugs used in 1 to 3 years will escape. In addition, danazol, acetate, high-dose ketoconazole match Xilong were used in clinic, but the side effect is too large, the use of less. Eugster found that the antitumor drug tamoxifen treatment effect is good, the Chen Ruimin also used the drug treatment of 5 cases of patients achieved a certain effect, the drug and estradiol binding to estrogen receptors, estrogen levels decline. Worth further exploration. GnRH agonist treatment effect is not good, but the peripheral sex hormone induced brain activation of GnRH agonist is effective, and can effectively improve the continuation of epiphyseal maturity, final height, has fewer side effects. The abnormal bone can be used: bisphosphonates inhibit bone resorption; bone by curettage, treatment and prevention of fracture deformity. Special complications such as bone disease caused by skull base or orbital bone fibrosis caused by optic foramen stenosis cause visual impairment, even blindness, can try surgical treatment. McCune-Albright syndrome is characterized by a typical triad, which is easy to diagnose. However, if the lesions are not typical, it still needs to be differentiated from central precocious puberty, hyperparathyroidism, hyperthyroidism, ovarian cancer, neurocutaneous syndrome and Paget disease.