Cobblestone appearance | Radiology Signs

Answer:

A cobblestone appearance is produced when intersecting longitudinal and transverse ulcers isolate intervening islands of oedematous, surviving mucosa, so the mucosal surface is broken into raised polygonal blocks separated by linear clefts. It is the classic mucosal pattern of Crohn disease, where the deep longitudinal ulcers running along the mesenteric border are crossed by transverse fissures. On barium studies it appears as nodular filling defects separated by barium-filled ulcer lines; on CT and MR enterography the ulcers are seen as serpiginous high-signal or contrast-filled tracts between areas of intermediate-signal oedematous mucosa, usually with mural thickening, mural hyperenhancement and mesenteric changes. It is characteristic of Crohn disease but not exclusive to it: intestinal tuberculosis, lymphoma, radiation and ischaemic enteritis and some infections can reproduce it, and a cobblestone mucosa is separately described in Candida oesophagitis, Hirschsprung disease and eosinophilic gastritis. Discontinuous skip lesions and mesenteric-border predominance favour Crohn disease.

Why is it called so?

The raised islands of intact mucosa separated by the ulcer clefts resemble cobblestones set in a paved street.

Pathophysiology

Crohn disease begins as aphthous ulceration over lymphoid aggregates. These enlarge and coalesce into deep linear ulcers that track longitudinally along the mesenteric border, and transverse fissures develop between them as the transmural inflammation extends. The mucosa remaining between the intersecting ulcers is not destroyed but is oedematous and inflamed, so it stands proud of the ulcerated surface. The combination of depressed intersecting ulcer lines and elevated intervening mucosal islands creates the paved, blocky surface, and the transmural nature of the inflammation explains the accompanying fistulae, sinus tracts and fibrofatty proliferation.

Alternative names: Cobblestone mucosa, cobblestoning

Other associated named signs: Comb sign, string sign of Kantor, creeping fat and fibrofatty proliferation, and the target or double halo sign of mural stratification

References

1. Yao T, Okada M, Fuchigami T, Iida M, Takenaka K, Date H, et al. The relationship between the radiological and clinical features in patients with Crohn’s disease. Clin Radiol. 1989;40(4):389-92. PMID: 2758748.