**Core Concept**
Diffuse type of gastric cancer, also known as linitis plastica or Bormann type IV, is a subtype of gastric adenocarcinoma characterized by its diffuse infiltration of the stomach wall by neoplastic cells. This type of cancer is often associated with a specific genetic mutation that distinguishes it from other forms of gastric cancer.

**Why the Correct Answer is Right**
The diffuse type of gastric cancer is typically associated with a mutation in the CDH1 gene, which encodes for E-cadherin, a protein crucial for cell-cell adhesion. This mutation leads to a loss of cell adhesion, allowing cancer cells to infiltrate and spread throughout the stomach wall. The CDH1 mutation is a hallmark of diffuse gastric cancer and is often used as a diagnostic marker.

**Why Each Wrong Option is Incorrect**
**Option A:** This answer choice is incorrect because it is not a specific mutation associated with diffuse gastric cancer. While genetic alterations are common in gastric cancer, the CDH1 mutation is the most relevant to diffuse type.
**Option B:** This answer choice is incorrect because it refers to a mutation seen in intestinal-type gastric cancer, which is a different subtype of gastric cancer.
**Option C:** This answer choice is incorrect because it refers to a mutation seen in other types of cancer, such as breast or ovarian cancer, and is not specifically associated with diffuse gastric cancer.

**Clinical Pearl / High-Yield Fact**
The CDH1 mutation is an autosomal dominant trait, meaning that a single copy of the mutated gene is enough to increase the risk of diffuse gastric cancer. Individuals with a family history of diffuse gastric cancer or a known CDH1 mutation should undergo regular screening and genetic counseling.

**Correct Answer:** B.