Internal Medicine Board Review Weekly Image Challenge: Left flank pain

Start out your Friday morning with our Radiology Challenge, featuring an Internal Medicine board exam-style image question:


47-year-old female with a past medical history of lupus and hypertension presents to the emergency department left flank pain for 8 hours. She has never experienced this pain previously. The pain is 10/10 in intensity, and nothing makes it better or worse. On physical exam, she is writhing in pain and is moderately tender to palpation at the left costovertebral angle. Labs are ordered and a CT scan has already been ordered by the time the hospitalist sees the patient. Based on the image below, which laboratory test will the hospitalist look to for making the diagnosis?


USMLE Step 1 Exam Question - Image Challenge


A. Lipase

B. White blood cell (WBC) count

C. Carcinoembryonic antigen (CEA)

D. Urinalysis



The non-contrast axial CT slice depicted above demonstrates posterior left upper quadrant stranding. Stranding on its own is suggestive of inflammation, but it is not immediately clear on the CT scan what the source of the stranding is. The stranding appears to be most closely associated with the tail of the pancreas. However, the descending colon, the spleen, and the left kidney all lie in the vicinity and could potentially be the cause of the patient’s pain. Choice A (Serum lipase) would confirm whether or not the source of the stranding is the pancreas and thus confirm the diagnosis of focal pancreatitis of the tail.


Explanation of incorrect answers:


  • Choice B (WBC count) would only be able to confirm the presence of a non-specific inflammatory process but would offer no utility in isolating its source.
  • Choice C (CEA) is a protein normally produced by intestinal cells in the fetus. Because it is also produced by some malignancies, most notably colon cancer, it can be used to monitor for cancer recurrence.
  • Choice D (Urinalysis) offers no help in determining the source of the intraperitoneal stranding seen on this patient’s CT scan.

    You can see all the previous ABIM Exam image of the week blog posts at the Knowmedge Blog. You can also find additional topics and questions directly from the Knowmedge Internal Medicine ABIM Board Exam Review Questions QVault.

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