TAILIEUCHUNG - Chapter 054. Skin Manifestations of Internal Disease (Part 25)

Palpable purpura are further subdivided into vasculitic and embolic. In the group of vasculitic disorders, cutaneous small-vessel vasculitis, also known as leukocytoclastic vasculitis (LCV), is the one most commonly associated with palpable purpura (Chap. 319). Underlying etiologies include drugs (., antibiotics), infections (., hepatitis C virus), and autoimmune connective tissue diseases. Henoch-Schönlein purpura is a subtype of acute LCV that is seen primarily in children and adolescents following an upper respiratory infection. The majority of lesions are found on the lower extremities and buttocks. Systemic manifestations include fever, arthralgias (primarily of the knees and ankles), abdominal pain, gastrointestinal bleeding,. | Chapter 054. Skin Manifestations of Internal Disease Part 25 Palpable purpura are further subdivided into vasculitic and embolic. In the group of vasculitic disorders cutaneous small-vessel vasculitis also known as leukocytoclastic vasculitis LCV is the one most commonly associated with palpable purpura Chap. 319 . Underlying etiologies include drugs . antibiotics infections . hepatitis C virus and autoimmune connective tissue diseases. Henoch-Schonlein purpura is a subtype of acute LCV that is seen primarily in children and adolescents following an upper respiratory infection. The majority of lesions are found on the lower extremities and buttocks. Systemic manifestations include fever arthralgias primarily of the knees and ankles abdominal pain gastrointestinal bleeding and nephritis. Direct immunofluorescence examination shows deposits of IgA within dermal blood vessel walls. In polyarteritis nodosa specific cutaneous lesions result from a vasculitis of arterial vessels or there may be an associated LCV. The arteritis leads to ischemia of the skin and this explains the irregular outline of the purpura see below . Several types of infectious emboli can give rise to palpable purpura. These embolic lesions are usually irregular in outline as opposed to the lesions of LCV which are circular in outline. The irregular outline is indicative of a cutaneous infarct and the size corresponds to the area of skin that received its blood supply from that particular arteriole or artery. The palpable purpura in LCV are circular because the erythrocytes simply diffuse out evenly from the postcapillary venules as a result of inflammation. Infectious emboli are most commonly due to gramnegative cocci meningococcus gonococcus gram-negative rods Enterobacteriaceae and gram-positive cocci Staphylococcus . Additional causes include Rickettsia and in immunocompromised patients Candida and opportunistic fungi. The embolic lesions in acute meningococcemia are found primarily on the