A 28-year-old woman with Crohn's disease involving the terminal ileum and colon (L3, B1 Montreal classification) has failed azathioprine. She is steroid-dependent. Anti-TNF therapy is being considered. Which serological marker in Crohn's disease is associated with complicated disease behaviour (stricturing/penetrating) and ileal involvement?

• A Perinuclear anti-neutrophil cytoplasmic antibodies (pANCA)
• B Anti-goblet cell antibodies
• C Anti-epithelial cell antibodies
• D Anti-Saccharomyces cerevisiae antibodies (ASCA) ✓

Explanation

ASCA (IgG and IgA) are found in approximately 60–70% of Crohn's disease patients and only 5–10% of ulcerative colitis patients. In CD, high ASCA titres are associated with ileal involvement, earlier age of onset, and complicated disease phenotype (stricturing/B2 or penetrating/B3 behaviour). pANCA is characteristically associated with ulcerative colitis (60–70%) and rarely with Crohn's disease. The ASCA+/pANCA- serotype is typical of Crohn's disease while pANCA+/ASCA- is typical of UC.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.