HCV infection has been found in most patients with EMC. Symptomatic cryoglobulinemia is mediated by the deposition of antigen-antibody complexes in small- and medium-sized arteries. Clinical manifestations of mixed cryoglobulinemia include palpable purpura (which is suggestive of vasculitis), nonspecific systemic symptoms (eg, myalgias, fatigue), arthralgias, lymphadenopathy, hepatosplenomegaly, peripheral neuropathy, and hypocomplementemia (often demonstrated by a decrease in C4 levels). Renal disease is present in a large number of patients with EMC; renal manifestations include hematuria, acute and chronic renal failure, and nephritic syndrome. A diagnosis of mixed cryoglobulinemia is typically made from the history, presence of skin purpura, and low complement levels and circulating cryoglobulins found on laboratory testing. This patient has no history of exposure to a new drug or environmental agent to suggest a diagnosis of an acute hypersensitivity reaction or insect bite. The physical examination findings are not compatible with cellulitis. Neither cellulitis nor an acute hypersensitivity reaction would explain the laboratory abnormalities in this patient. There is no history of travel to an area endemic for Rocky Mountain spotted fever, and the 2-week history of slowly progressive symptoms and the lack of systemic toxicity rule against Rocky Mountain spotted fever.
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Seminars in Medical Practice
Hospital Physician Board Review Manuals
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Updated 11/6/07 kkj