**Core Concept:** Crohn's disease is a type of inflammatory bowel disease (IBD) that affects the gastrointestinal tract. It is a chronic condition characterized by inflammation and ulceration of the gastrointestinal tract, leading to various symptoms and complications.

**Why the Correct Answer is Right:** Crohn's disease typically involves the entire gastrointestinal tract and can be located in any part, from the mouth to the anus. This makes it different from ulcerative colitis, which primarily affects the colon and rectum. The disease is characterized by a transmural inflammation, meaning it involves the entire thickness of the intestinal wall.

**Why Each Wrong Option is Incorrect:**

A. Granulomas: Crohn's disease often presents with granulomas, which are non-caseating granulomas (inflammatory lesions) found in the affected tissue.

B. Localized inflammation: Crohn's disease is characterized by transmural inflammation, which means it affects the entire intestinal wall, making option B incorrect.

C. Involvement of the terminal ileum and cecum: Although these areas can be affected in Crohn's disease, the question states that the features are "all except", meaning that all could be present, but not all must be present.

D. Mucosal inflammation: While mucosal inflammation is a feature of Crohn's disease, it is not the sole feature; the disease encompasses transmural inflammation and involves the entire intestinal wall.

**Clinical Pearl:** Understanding the unique features of Crohn's disease helps differentiate it from other conditions like ulcerative colitis, which primarily affects the colon and rectum, and from other inflammatory bowel diseases.

**Correct Answer:** D. Mucosal inflammation