**Core Concept**
Ameboid ulcer is a type of gastric ulcer characterized by its irregular, amoeba-like shape and rapid progression. This condition is often associated with a loss of gastric mucosal integrity and a subsequent increase in acid production.

**Why the Correct Answer is Right**
Ameboid ulcers are typically seen in conditions where there is an imbalance between acid production and mucosal defense mechanisms, such as in the context of Zollinger-Ellison syndrome. This syndrome is caused by excessive production of gastrin, leading to an overproduction of gastric acid and subsequent mucosal damage. The rapid progression of ameboid ulcers is due to the continued acid production and the inability of the mucosa to keep up with the acid load.

**Why Each Wrong Option is Incorrect**
**Option A:** Gastric ulcers due to Helicobacter pylori infection typically present as chronic, non-bleeding ulcers and do not exhibit the rapid progression characteristic of ameboid ulcers.
**Option B:** Duodenal ulcers are often seen in individuals with a history of NSAID use or stress, but they do not typically present with the same rapid progression as ameboid ulcers.
**Option C:** Malignant ulcers may present with irregular borders and rapid growth, but they are not typically associated with the same loss of gastric mucosal integrity as seen in ameboid ulcers.

**Clinical Pearl / High-Yield Fact**
Ameboid ulcers are a classic feature of Zollinger-Ellison syndrome, and their presence should raise suspicion for this condition in patients with severe peptic ulcer disease.

**Correct Answer:** D.