1. A 55 y/o female is found to have an abdominal mass. A surgery a mass was found within the mesentery abutting the stomach and small intestine. Immunohistochemistry found the cells of interest to be positive for smooth muscle actin but negative for CD34, CD117, S-100, and desmin. Based on the histologic immunohistochemical findings, the best diagnosis is:

2. A 70 y/o woman undergoes a screening colonoscopy and is found to have a right sided polyp. Based on the histologic findings in the images, the best diagnosis is:

3. A 60 y/o female undergoes a screening colonoscopy and is found to have a single left-sided colon polyp. Based on the histologic findings in the images for this case, the best diagnosis is:

4. A 45 y/o male with a history of constipation and occasional bright read blood on his stool undergoes a colonoscopy. A polypoid lesion is identified in the left colon, and a biopsy is performed. Based on the histologic findings, the best diagnosis is:

5. A 55 y/o male is found to have a mass lesion in the anal canal just above the dentate line. Based on the history and histologic findings in the images, the best diagnosis is:

6. A 45 y/o woman undergoes colonoscopy for chronic diarrhea. No polyps or ulcerations are found. The mucosal surface is somewhat discolored, and multiple biopsies are obtained. Based on the histologic findings, the best diagnosis is:

7. A 35 y/o black male with a history of renal transplant and unspecified GI complaints undergoes colonoscopy for the evaluation of GVHD. Based on the histologic findings, the best diagnosis is:

8. A 45 y/o Asian male with a history of chronic hepatitis B presents to the ER with a liver mass by CT scan. Surgery is performed and representative images of the histology are shown. Based on the findings, the best diagnosis is:

9. A 35 y/o male with HIV presented to the ER with a h/o bloody diarrhea. Colonoscopy with multiple biopsies were performed. Based on the histologic findings in the images, the best diagnosis is:

10. A 55 y/o male with a history of intermittent bloody stool undergoes a colonoscopy. A large polyp is found and biopsied. Based on the histologic finding shown, what is the best diagnosis: