Biopsy of a small, rounded rectal polyp demonstrates glands and saw tooth crypts composed of a proliferation of goblet and columnar epithelial cells. No atypia is seen. This polyp is best classified as which of the following?
**Core Concept**
The biopsy findings suggest a polyp with a mixture of goblet and columnar epithelial cells, characteristic of a type of polyp that is typically benign and composed of mucinous and epithelial elements.
**Why the Correct Answer is Right**
The described polyp is likely a **mucosal polyp**, specifically a **hyperplastic polyp**. Hyperplastic polyps are small, usually rounded, and contain a mixture of goblet and columnar epithelial cells. They often have saw-tooth crypts and are commonly found in the rectum. These polyps are typically benign and do not harbor significant malignant potential.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely referring to a **adenomatous polyp**, which is a type of polyp that is composed of glandular epithelium and has a higher risk of malignant transformation. The biopsy findings do not suggest atypia, making this option incorrect.
* **Option B:** This option is likely referring to a **mucinous polyp**, which is a type of polyp that is composed primarily of mucinous epithelial cells. While mucinous polyps can occur in the rectum, the biopsy findings suggest a mixture of goblet and columnar epithelial cells, making this option incorrect.
* **Option D:** This option is likely referring to a **carcinoid polyp**, which is a type of polyp that is composed of neuroendocrine cells. The biopsy findings do not suggest neuroendocrine differentiation, making this option incorrect.
**Clinical Pearl / High-Yield Fact**
Remember that hyperplastic polyps are typically small, benign, and do not require removal unless they cause symptoms or are part of a larger polypoid lesion.
**Correct Answer:** C.