If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 3 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.
The AMA and Kaplan have teamed up to support you in reaching your goal of passing the USMLE® or COMLEX-USA®. If you're looking for additional resources, Kaplan provides free access to tools for pre-clinical studies, including Kaplan’s Lecture Notes series, Integrated Vignettes, Shelf Prep and more.
This month’s stumper
Your patient is extremely distressed at a worsening tightening of the skin developing around the face and hands. The patient also has epigastric pain radiating into the chest. There is no shortness of breath or hypertension. Chest x-ray is normal and BUN and creatinine are normal. Echocardiography shows a pulmonary artery pressure that is elevated. Pulmonary function testing is planned. The patient asks about her prognosis.
Which of the following represents the greatest difference between limited scleroderma (CREST syndrome) and diffuse systemic sclerosis?
A. Anti-centromere antibodies.
B. ANA.
C. Raynaud's phenomenon.
D. Esophageal dysmotility.
E. Hand involvement.
The correct answer is A.
Kaplan Medical explains why
Anti-centromere antibodies are present in almost all patients with CREST syndrome (90%) but in virtually no patients (less than 5%) with diffuse systemic sclerosis (scleroderma).
Why the other answers are wrong
Choice B: The ANA is present in the majority of patients with both syndromes.
Choice C, D and E: Raynaud's phenomenon, esophageal dysmotility, and hand involvement known as sclerodactyly are present in both syndromes. Esophageal dysmotility manifests as gastroesophageal reflux disease in both patient groups.
Tips to remember
Anti-centromere antibodies are present in CREST syndrome, but not in diffuse systemic sclerosis (scleroderma).
For more prep questions on USMLE Steps 1, 2 and 3, view other posts in this series.
