**Core Concept**
A leiomyoma is a type of smooth muscle tumor that can occur in the gastrointestinal tract, including the esophagus. On a barium swallow study, leiomyomas can exhibit characteristic radiographic features that aid in their diagnosis.

**Why the Correct Answer is Right**
Leiomyomas typically appear as well-defined, rounded or ovoid masses on barium swallow, often with a smooth or lobulated surface. They may be located in the esophageal wall, causing a polypoid projection into the lumen. The characteristic feature of leiomyomas is their ability to displace the surrounding esophageal mucosa, creating a clear boundary between the tumor and the normal esophageal wall.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because leiomyomas are not typically associated with ulceration or necrosis, which would be more characteristic of malignant tumors.

**Option B:** This option is incorrect because leiomyomas are not usually accompanied by significant esophageal narrowing or stricture, which would be more indicative of esophageal cancer or other obstructive lesions.

**Option C:** This option is incorrect because leiomyomas are not typically associated with a "corkscrew" or "corkscrew-like" appearance on barium swallow, which would be more characteristic of diffuse esophageal spasm or other motility disorders.

**Clinical Pearl / High-Yield Fact**
A key characteristic of leiomyomas on barium swallow is their ability to displace the surrounding esophageal mucosa, creating a clear boundary between the tumor and the normal esophageal wall. This feature can help differentiate leiomyomas from other esophageal lesions, such as esophageal cancer or infectious processes.

**Correct Answer:** C.