Case 3: Differential Diagnoses

Case 3 Index

What conditions are on your differential diagnosis?
Tension Pneumothorax
Incorrect. Although pneumothorax could result in pleuritic chest pain, Mary’s normal vitals and equal breath sounds bilaterally make this diagnosis unlikely. A small non-hemodynamically significant pneumothorax cannot be ruled out at this point, but even if present, would not explain the whole presentation. Keep trying!
Systemic lupus erythematosus
Correct! The constellation of pleuritic chest pain, arthritis, malar rash, low-grade fever, oral ulcer, and weight loss in a young woman with family Hx of autoimmune disease is certainly concerning for SLE. Great job!
Drug-induced hypersensitivity syndrome
Incorrect. Mary has not started any new drugs recently, so a drug reaction is unlikely. However, it is excellent to keep a broad differential for any systemic inflammatory disease, including infection, malignancy, autoimmune disease, drug reactions, and endocrinopathies. Keep trying!
Rheumatoid arthritis
Correct! Mary is presenting with arthritis and systemic symptoms, which could also be explained by RA, especially given history in her family. Start thinking about what further studies you would like to order to help distinguish between your top differentials.
Community acquired pneumonia
Incorrect. Although CAP could certainly present with pleuritic chest pain, low-grade fever, and malaise, the prolonged nature of Mary’s symptoms and additional findings, such as joint and skin involvement, make CAP unlikely in this case. Rheumatic fever could present with a constellation of cardiac, MSK, and cutaneous findings, but we would expect a history of untreated streptococcal infection (which have become very rare with wide-spread availability of testing and antibiotics, at least n the US).
Acute leukemia
Correct! Acute leukemia (either myeloid or lymphoblastic) can present with fatigue, weight loss, joint pain/swelling, and rash of almost any kind, making it a very important differential diagnosis to consider. Strong work!
Incorrect. While patients with fibromyalgia experience fatigue and joint pains, the rest of Mary’s symptoms point to an inflammatory condition.
Correct! The constellation of pulmonary/cardiac, skin, and joint findings in a young woman should make you think of sarcoidosis. Although her rash is more consistent with a different diagnosis and pericarditis would not be a typical cardiac finding in sarcoid (as opposed to heart block, arrhythmias, cardiomyopathy), it should still be on your differential.
Correct! Patient is presenting with rash, arthritis, chest pain, and weight loss, which could be consistent with endocarditis with embolic phenomena and immune complex deposition. Mary does not have clear risk factors for infective endocarditis, but it still behooves us to rule it out.
Incorrect. Parvovirus is an excellent thought for a patient with malar rash and joint pains, but the presence of cardiac symptoms, weight loss, and absence of exposure to small children make parvovirus less likely. Additionally, the classic “slapped cheeks” rash occurs more commonly in children, while adults generally present with joint pain and swelling.
Idiopathic pericarditis
Incorrect. Mary certainly does have a constellation of findings consistent with pericarditis, but the additional symptoms of weight loss, fatigue, joint pains, and rash point to a secondary cause.


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