A 43-year-old man comes to the physician because of weakness and arthralgias for the last four months. He also has a pruritic rash on his legs that appeared two months ago. He denies fever or chills and his weight has been stable.
His blood pressure is 140/90 mm Hg and pulse is 84/min. A rash is present on both lower extremities below the knees that consist of many erythematous macules.
Laboratory results are as follows:

Which of the following would be most helpful in establishing the diagnosis in this patient?

Question

A 43-year-old man comes to the physician because of weakness and arthralgias for the last four months.  He also has a pruritic rash on his legs that appeared two months ago.  He denies fever or chills and his weight has been stable.
His blood pressure is 140/90 mm Hg and pulse is 84/min.  A rash is present on both lower extremities below the knees that consist of many erythematous macules.
Laboratory results are as follows:

Which of the following would be most helpful in establishing the diagnosis in this patient?

Quizplus · Accepted Answer

11ec193a_98fc_bb60_853d_5923234ddd45_MD0002_00 This patient's presentation is consistent with mixed cryoglobulinemia causing glomerulonephritis. Cryoglobulinemia is classified as either type I or mixed (types II and III). Diagnosis is suggested by elevated cryoglobulins (cryocrit), ESR, CRP, autoantibodies (e.g., RF, ANA), and clinical symptoms (summarized in the above table). Mixed cryoglobulinemia is commonly associated with hepatitis C and elevated liver function tests, and more than 60% of patients with hepatitis C have cryoglobulins. Approximately 20% of patients with cryoglobulinemia develop renal disease, which is usually glomerulonephritis from hepatitis C-containing immune complexes. Patients with hepatitis C-associated cryoglobulinemia have a higher risk of developing lymphoma up to 5-10 years later. Treatment involves eradicating HCV, immunosuppression (eg, prednisone, cyclophosphamide), and/or plasmapheresis for moderate-severe cryoglobulinemia. (Choice A) Anti-phospholipid antibody syndrome (APS) can also cause anemia, thrombocytopenia, livedo reticularis, and glomerulonephritis. However, this patient has increased AST and ALT and low albumin, suggesting chronic liver disease. Also, most patients with APS have thrombotic episodes (eg, DVT, strokes). (Choice B) Bone marrow biopsy is more useful in type I cryoglobulinemia to diagnose an underlying hematological condition with bone marrow involvement. However, this patient likely has mixed cryoglobulinemia and would not need a bone marrow biopsy. (Choice C) Serum protein electrophoresis can help diagnose underlying plasma cell disorders (eg, multiple myeloma or Waldenström's macroglobulinemia), but they are associated more with type I than mixed cryoglobulinemia. (Choice D) Heroin users can develop membranous nephropathy (due to hepatitis B), membranoproliferative glomerulonephritis (due to hepatitis C), or focal segmental glomerulosclerosis. However, this patient's presentation is consistent with vasculitis. Viral serologies are more likely to give a correct diagnosis in this patient given the low white cell count, thrombocytopenia, and increased AST/ALT. Educational objective: Mixed cryoglobulinemia is commonly associated with hepatitis C and can cause glomerulonephritis. Treatment includes eradicating hepatitis C and immunosuppression and/or plasmapheresis for cryoglobulinemia. __________ References: Mixed cryoglobulinemia. (http://www.ncbi.nlm.nih.gov/pubmed/18796155) Hepatitis C virus infection in patients with essential mixed cryoglobulinemia. (http://www.ncbi.nlm.nih.gov/pubmed/1326246)

A 43-Year-Old Man Comes to the Physician Because of Weakness