Case 3: Diagnostic Testing

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Basic laboratory results
What does the EKG show?
Correct! Pericarditis presents with diffuse ST-elevations and depressed PR intervals. This findings further supports our hypothesis that Mary has pericarditis based on the character of her pain and the presence of friction rub.
Incorrect. Great job noticing the ST elevations. However, they do not follow a particular vascular distribution but are rather diffuse. Think about what other conditions can present with these findings and try again!
Incorrect. Tamponade is mostly a clinical diagnosis, which classically presents with the triad of hypotension, elevated JVD, and distant heart sounds (also known as Beck triad). A suggestive sign on an EKG is electrical alternans.
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Chest Xray 
Normal (source: Dr. Henry Knipe,, click to navigate to page)
CT chest w/contrast
No pulmonary embolism, but pericardial thickening. Click on image to navigate to radiopedia and scroll through the full CT. [Source: Dr. Andrew Dixon,]
Choose the most high yield diagnostic test to perform next!
Bone marrow biopsy
Incorrect. With a normal WBC differential and peripheral smear, bone marrow biopsy is not currently indicated. Pancytopenia can be a typical lupus manifestation, so unless testing for SLE and other autoimmune diseases is negative or her counts do not improve with treatment, bone marrow biopsy is not indicated at this time. 
Anti-nuclear antibodies (ANA) and extractable nuclear antigens (ENA)
Correct! Mary’s constellation of symptoms is concerning for SLE. To confirm our diagnosis, we would like to see positive ANA, anti-dsDNA and/or anti-Smith antibodies (both are specific for SLE). Other autoantibodies, such as anti-SSA/SSB, could also be positive. Anti-DsDNA, anti-Smith, anti-SSA/SSB are often included under the ENA (extractable nuclear antigen) panel, that helps clarify which specific ANAs are present. Check back in soon for RheumSim antibody tutorial to help make sense of ANAs, specific antibodies, and their disease associations. 
RF, anti-CCP, and X-Rays of hands 
Correct! We would like to rule out RA as a cause of her symptoms and look for SLE-RA overlap syndrome.
Correct! Elevated inflammatory markers would support our hypothesis that systemic inflammation is present. In addition, after the diagnosis and treatment are clarified, monitoring these levels could be one additional way to assess response to therapy.
Blood cultures
Correct! We need to rule out bacteremia related to endocarditis or other nidus of infection.
IL-2 receptor level
Incorrect! The level of soluble IL-2R is significantly elevated in hemophagocytic lymphohistiocytosis (HLH). While autoimmune, infectious, and malignant conditions can lead to secondary HLH, Mary’s presentation does not meet criteria for this life-threatening hyper-inflammatory syndrome (see H-score here and HLH-2004 criteria here that can help diagnose HLH)
Complement levels
Correct! Part of SLE pathogenesis involves formation of immune complexes (antigen + antibody + complement) which deposit in tissue and cause inflammation and damage. Thus, complement levels are often low in active SLE.
Skin biopsy
Incorrect. While tissue pathology can often help with diagnosis, and skin is an accessible organ, her rash is typical for a malar rash and biopsy is not necessary, if our suspicions for what is going on are confirmed with other less-invasive tests.
Explanation: Correct! Although Mary does not appear to have clinical evidence of tamponade, evaluating for a pericardial effusion and valvular vegetations will be helpful, given the differential diagnosis we constructed previously.
Kidney biopsy
Explanation: Incorrect. Although kidney biopsy is important in diagnosis and classification of lupus nephritis, Mary’s normal renal function and bland UA argue against kidney involvement at this point.

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Case 3 Index
Case 3 Introduction
Case 3 Review of Systems

Case 3 Physical Exam
Case 3 Differential Diagnoses