The telangiectasias consist of focal dilation of postcapil

Hereditary hemorrhagic telangiectasia, also referred to as Osler-Weber-Rendu syndrome, is a rare autosomal dominant disorder that is characterized by multiple telangiectatic lesions involving the skin, mucous membranes, and viscera.

One form of the disorder, characterized by a high frequency of symptomatic pulmonary arteriovenous malformations and cerebral abscesses, has been identified. Both ENG and ALK-1 encode putative receptors for transforming growth factor-beta (TGF-β) superfamily that play a critical role for proper development of the blood vessels.17

lary venules with connections to dilated arterioles, initially through capillaries and later directly. Perivascular mononuclear cell infiltrates also are observed. The vessels of HHT show a discontinuous endothelium and an incomplete smooth muscle cell layer.

The surrounding stroma lacks elastin. Thus, the bleeding tendencies are thought to be because of mechanical fragility of the abnormal vessels.6 Lesions usually appear in affected persons by the age of 40 years, and they increase in number with age.6,18-21 Clinical Findings.

On clinical examination, venous lakes and papular, punctate, matlike, and linear telangiectasias appear on all areas of the skin and mucous membranes, with a predominance of lesions on and under the tongue Thus, the severity of the disorder often can be gauged by the age at which the nosebleeds begin, with the most severely affected patients experiencing recurrent epistaxis during childhood.

Cutaneous changes usually begin at puberty and progress throughout life. Bleeding can occur in virtually every organ, with GI, oral, and urogenital sites most commonly affected (Fig. 25.5). In the GI tract, the stomach and duodenum are more frequent sites of bleeding than is the colon.

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Other features may include hepatic and splenic arteriovenous shunts, as well as intracranial, aortic, and splenic aneurysms. Pulmonary arteriovenous fistulas are associated with oxygen desaturation, hemoptysis, hemothorax, brain abscess, and cerebral ischemia caused by paradoxical emboli. Cirrhosis of the liver has been reported in some families

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