A 22-year-old woman comes to the office with a 3-week history of rash on her face and upper back, which first appeared during a spring break trip to a Florida beach. During the trip, she also had a flu-like illness and continues to experience fatigue and aching pain in her joints. The patient has no prior medical conditions and takes no medications. She occasionally drinks alcohol but does not use tobacco or illicit drugs. She is sexually active with multiple partners. Temperature is 38 C (100.4 F), blood pressure is 142/80 mm Hg, and pulse is 92/min and regular. Physical examination shows an erythematous, maculopapular rash on the face and upper back. Nontender, generalized lymphadenopathy is present. The lungs are clear on auscultation and a faint diastolic murmur is present. The abdomen is soft and nontender with mild splenomegaly. Laboratory results are as follows: Which of the following is the most appropriate next step in establishing this patient's diagnosis?

Question

A 22-year-old woman comes to the office with a 3-week history of rash on her face and upper back, which first appeared during a spring break trip to a Florida beach.  During the trip, she also had a flu-like illness and continues to experience fatigue and aching pain in her joints.  The patient has no prior medical conditions and takes no medications.  She occasionally drinks alcohol but does not use tobacco or illicit drugs.  She is sexually active with multiple partners.  Temperature is 38 C (100.4 F), blood pressure is 142/80 mm Hg, and pulse is 92/min and regular.  Physical examination shows an erythematous, maculopapular rash on the face and upper back.  Nontender, generalized lymphadenopathy is present.  The lungs are clear on auscultation and a faint diastolic murmur is present.  The abdomen is soft and nontender with mild splenomegaly.  Laboratory results are as follows:  Which of the following is the most appropriate next step in establishing this patient's diagnosis?

Quizplus · Accepted Answer

11ec25c8_d23a_0f94_bc81_3ba4512e6d8c_MD0003_00 This young woman's rash and multisystemic symptoms suggest systemic lupus erythematosus (SLE). Common presenting manifestations include constitutional symptoms (eg, flu-like symptoms), arthralgias, and photosensitive rash (on classic sun-exposed areas following a beach trip). New murmur and hypertension indicate heart and kidney involvement. Active SLE can produce hematologic manifestations (eg, mild thrombocytopenia, anemia, leukopenia), lymphadenopathy, and splenomegaly. The pretest probability of SLE increases when several classic findings are present, and serologic testing for antinuclear antibodies (ANA) should be ordered. Although ANA is positive in nearly 100% of patients with SLE over the disease course (ie, highly sensitive), a positive ANA occurs in many conditions and healthy individuals (ie, poorly specific). Therefore, a positive ANA should prompt confirmatory testing with SLE-specific autoantibodies (eg, anti-double-stranded DNA). A negative ANA in this patient would significantly lower the likelihood of SLE, prompting investigation of other causes. (Choice B) Bone marrow biopsy can assess for leukemia or lymphoma (a potential cause of splenomegaly, fever, or cytopenia). However, photosensitive rash, arthralgias, and new murmur are uncommon, and increase the diagnostic likelihood of SLE. Therefore, ANA should be tested prior to a more invasive workup. (Choice C) Reactive heterophile antibodies are diagnostic of infectious mononucleosis, which can manifest with fevers, rash, and lymphadenopathy. However, pharyngitis and lymphocytosis are usually observed, and this patient's leukopenia is unusual. (Choice D) Blood cultures can assess for bacterial endocarditis, associated with new murmur, fatigue, fevers, and anemia. However, this patient lacks endocarditis risk factors (eg, intravenous drug use, artificial valve); a photosensitive, maculopapular rash is not expected. (Choice E) This patient's age and sexual history increases her risk for disseminated gonococcal infection (DGI), associated with arthralgias, rash, and fevers. However, rash in DGI is typically pustular rather than maculopapular and not associated with sun exposure. Moreover, pancytopenia and splenomegaly are uncommon. (Choice F) Cryoglobulinemia associated with chronic hepatitis B and C can cause migratory arthritis and maculopapular rash; acute hepatitis classically causes hepatomegaly (with anorexia and right upper quadrant pain). However, neither would explain this patient's photosensitive rash or diastolic murmur. Educational objective: A photosensitive rash, along with multisystemic symptoms (eg, arthralgias, pancytopenia, splenomegaly), raises concern for systemic lupus erythematosus (SLE). The antinuclear antibody assay is highly sensitive for SLE. References: Systemic Lupus Erythematosus. Ann Intern Med. 2013;159(7):ITC4-1 (http://www.ncbi.nlm.nih.gov/pubmed/1) Rational use of blood tests in the evaluation of rheumatic diseases. Mo Med. 2012 Jan-Feb;109(1):59-63. (http://www.ncbi.nlm.nih.gov/pubmed/22428449) Sensitivity and specificity of ANA and anti-dsDNA in the diagnosis of systemic lupus erythematosus: a comparison using control sera obtained from healthy individuals and patients with multiple medical problems. "Asian Pac J Allergy Immunol. 2013 Dec;31(4):292-8. (http://www.ncbi.nlm.nih.gov/pubmed/24383972)

A 22-Year-Old Woman Comes to the Office with a 3-Week