tailieunhanh - Chapter 109. Disorders of Platelets and Vessel Wall (Part 11)

Metabolic and Inflammatory Disorders Acute febrile illnesses may result in vascular damage. This can result from immune complexes containing viral antigens or the viruses themselves. Certain pathogens, such as the rickettsiae causing Rocky Mountain spotted fever, replicate in endothelial cells and damage them. Vascular purpura may occur in patients with polyclonal gammopathies but more commonly in those with monoclonal gammopathies, including Waldenstrom's macroglobulinemia, multiple myeloma, and cryoglobulinemia. Patients with mixed cryoglobulinemia develop a more extensive maculopapular rash due to immune complex-mediated damage to the vessel wall. . | Chapter 109. Disorders of Platelets and Vessel Wall Part 11 Metabolic and Inflammatory Disorders Acute febrile illnesses may result in vascular damage. This can result from immune complexes containing viral antigens or the viruses themselves. Certain pathogens such as the rickettsiae causing Rocky Mountain spotted fever replicate in endothelial cells and damage them. Vascular purpura may occur in patients with polyclonal gammopathies but more commonly in those with monoclonal gammopathies including Waldenstrom s macroglobulinemia multiple myeloma and cryoglobulinemia. Patients with mixed cryoglobulinemia develop a more extensive maculopapular rash due to immune complex-mediated damage to the vessel wall. Patients with scurvy vitamin C deficiency develop painful episodes of perifollicular skin bleeding as well as more systemic bleeding symptoms. Vitamin C is needed to synthesize hydroxyproline an essential constituent of collagen. Patients with Cushing s syndrome or on chronic glucocorticoid therapy develop skin bleeding and easy bruising due to atrophy of supporting connective tissue. A similar phenomena is seen with aging where following minor trauma blood spreads superficially under the epidermis. This has been termed senile purpura and it is most common on skin that has been previously damaged by sun exposure. Henoch-Schonlein or anaphylactoid purpura is a distinct self-limited type of vasculitis that occurs in children and young adults. Patients have an acute inflammatory reaction with IgA and complement components in capillaries mesangial tissues and small arterioles leading to increased vascular permeability and localized hemorrhage. The syndrome is often preceded by an upper respiratory infection commonly with streptococcal pharyngitis or is triggered by drug or food allergies. Patients develop a purpuric rash on the extensor surfaces of the arms and legs usually accompanied by polyarthralgias or arthritis abdominal pain and hematuria from focal .