C17.2

HCC Category Mapping

What This Code Means

Cancer that develops in the ileum, which is the final and longest section of the small intestine.

Coding Tips

• •Document whether this is primary ileal cancer or secondary involvement; ileal cancers are uncommon
• •Note any association with Crohn's disease or other predisposing conditions if present

Clinical Significance

Malignant neoplasm of the ileum affects the longest and most distal segment of the small intestine. The ileum is a relatively common site for carcinoid (neuroendocrine) tumors and lymphoma compared to other small bowel segments. Ileal cancers may present with obstruction, intussusception, or bleeding, and patients with Crohn disease affecting the ileum have an increased risk of malignancy. Accurate coding ensures risk adjustment reflects the complex care these patients require.

Documentation Requirements

• ✓Confirmed ileal location as the primary malignant site
• ✓Histological type (neuroendocrine/carcinoid tumors are common in this location)
• ✓Any history of Crohn disease or other predisposing inflammatory conditions
• ✓Stage of disease including mesenteric lymph node involvement
• ✓Distinction from Meckel diverticulum malignancy (C17.3)

Commonly Confused Codes