1. A 75 y/o male undergoes a colon resection for a mass. Representative images of the lesion are shown. The cells of interest are Cytokeratin, cyclin D1, CD5, chromogranin, synaptophysin, and S-100 negative, and are positive for CD45 and CD20. Based on these findings, the best answer is:

2. A 40 y/o male presented with mildly elevated AST and ALT ( 3 ½ times normal) lab values. Studies for hepatitis A, B, and C were negative. ANA titer was 1:80, but no history of autoimmune disease was present. The patient was significantly overweight, and noted to have a fasting glucose level of 157. A liver biopsy was performed. Based on the history and histologic findings (trichrome stain not shown shows increased pericellular fibrosis), the best diagnosis is:

3. A 45 y/o patient was found to have a mesenteric mass. Histologic images are shown. Closed examination found the spindle cell proliferation to infiltrate the outer intestinal wall and adipose tissue. Foam and inflammatory cells were scarce. S-100, CD117, and CD34 were negative. Based on these findings, the best answer is:

4. A 55 y/o male undergoes a colon resection for an unrelated mass and is found to have a lesion within the wall of the colon. Based on the histological images, the best diagnosis is:

5. Mesenteric fibromatosis is associated with which of the following:

6. Which of the following is most commonly associated with primary sclerosing cholangitis?

7. A 35 y/o HIV patient presents with an acute abdomen. At surgery the ileocecal area was perforated. Representative histologic findings are presented in the images. Based on the history and findings, the best diagnosis is:

8. A 45 y/o female presents to the ER with right upper quadrant pain after eating fatty meals. Ultrasound showed cholelithiasis, and a cholecystectomy was scheduled. Upon pathologic examination, a mass was found in the fundus of the gallbladder. Based on the histologic findings, the best diagnosis is:

9. A 19 y/o female presents with embarrassing diarrhea and flatulence over the past month. The symptoms began after a recent mission trip with her church to Romania. EGD and colonoscopy were negative for any gross disease. Duodenal biopsy images are shown. Based on the history and histologic findings, which of the following stains would be most helpful in highlighting the pathology:

10. A 30 y/o male presents with an elevated bilirubin. ERCP showed a “string of beads” appearance, and the liver biopsy showed changes represented by the histologic images showed. Based on the findings, the most likely diagnosis is: