A 32-year-old man comes to the office due to 2 weeks of fever, malaise, and arthralgia. Temperature is 38.2 C (100.8 F) and pulse is 102/min. Physical examination reveals several enlarged cervical, axillary, and inguinal lymph nodes and a diffuse maculopapular skin rash. Serum aminotransferase levels are elevated. During further testing, the patient's serum is added to a mixture of cardiolipin, cholesterol, and lecithin, which leads to extensive clumping and flocculation. Evaluation for antibodies directed against which of the following is the best next step in management of this patient?

Question

A 32-year-old man comes to the office due to 2 weeks of fever, malaise, and arthralgia.  Temperature is 38.2 C (100.8 F) and pulse is 102/min.  Physical examination reveals several enlarged cervical, axillary, and inguinal lymph nodes and a diffuse maculopapular skin rash.  Serum aminotransferase levels are elevated.  During further testing, the patient's serum is added to a mixture of cardiolipin, cholesterol, and lecithin, which leads to extensive clumping and flocculation.  Evaluation for antibodies directed against which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

11ec160b_385f_1790_9249_f15bb4af92fc_MD0001_00 This patient has fever, arthralgias, diffuse lymphadenopathy, elevated aminotransferases, and widespread maculopapular rash raising suspicion for secondary syphilis. Syphilis is a multistage infection caused by the spirochete Treponema pallidum. Diagnostic screening and confirmation rely primarily on serologic testing. Nontreponemal serologic tests (rapid plasma reagin, VDRL) mix a patient's serum with a cardiolipin-cholesterol-lecithin antigen. Aggregation or flocculation (clumping) indicates the presence of anticardiolipin antibodies in the patient's serum. These antibodies form in response to the release of lipids from cells damaged by T pallidum. However, anticardiolipin antibodies are nonspecific; they can also develop in other treponemal (eg, yaws, pinta, bejel) and nontreponemal (eg, tuberculosis) infections and certain rheumatologic diseases (eg, lupus), which can lead to false-positive results. Positive nontreponemal screening requires diagnostic confirmation with treponemal serologic testing (eg, fluorescent treponemal antibody-absorption). Treponemal tests evaluate for antibodies that directly target T pallidum; patient serum is mixed with killed T pallidum to evaluate for antibody adherence using immunofluorescence. Patients with positive nontreponemal and treponemal tests are considered infected with syphilis. (Choice A) Lyme disease is caused by the spirochete Borrelia burgdorferi. Patients with early Lyme disease often develop flulike symptoms and a bull's-eye rash (not a diffuse maculopapular rash). Serologic testing for IgM/IgG against Borrelia can aid in the diagnosis as the disease progresses. (Choice B) Rheumatoid factor is an antibody that targets the Fc portion of IgG. Elevations are often seen in patients with rheumatoid arthritis and other autoimmune diseases. (Choice C) Histoplasma capsulatum infection can be diagnosed by examining urine and serum for fungal antigens. Histoplasma infections usually present with prominent pulmonary manifestations rather than diffuse rash and lymphadenopathy. (Choice D) Antimitochondrial antibodies are present in >95% of cases of primary biliary cholangitis, which usually causes fatigue, pruritus, hepatomegaly, and elevated alkaline phosphatase. This patient's systemic maculopapular rash and diffuse lymphadenopathy make syphilis more likely. Educational objective: Syphilis is caused by the spirochete Treponema pallidum. Confirmation of the diagnosis requires 2 forms of serologic testing to prevent false-positive results. Nontreponemal tests (eg, rapid plasma reagin, VDRL) evaluate for anticardiolipin antibodies (nonspecific); treponemal tests evaluate for antibodies targeted against T pallidum.

A 32-Year-Old Man Comes to the Office Due to 2