Cottage loaf sign | Radiology Signs

Answer:

The cottage loaf sign describes the two-tier shape of the liver when part of it herniates through a right-sided diaphragmatic rupture. The herniated portion forms a rounded mass above the diaphragm (the hump), the intra-abdominal liver forms the larger lower tier, and the two are separated by a waist-like constriction at the diaphragmatic defect (the band), reproducing the shape of a traditional cottage loaf. It is best appreciated on coronal or sagittal reformats of CT or on MRI, which shows the diaphragmatic discontinuity directly. Right-sided ruptures are easily missed because the liver plugs the defect, so this sign is often the only clue. It must be separated from diaphragmatic eventration, in which the diaphragm is uniformly thinned but continuous with no muscular discontinuity, and from congenital Bochdalek, Morgagni and hiatal hernias.

Why is it called so?

The small rounded upper portion sitting on the larger lower portion with a waist between them resembles a traditional English cottage loaf.

Pathophysiology

Blunt trauma raises intra-abdominal pressure abruptly and tears the diaphragm, most often at its weaker posterolateral portion. On the right the liver both protects the diaphragm and, once a tear occurs, is forced through it by the persistent pressure gradient between abdomen and thorax. The rigid margins of the defect constrict the herniating liver at the point of passage, so the organ is waisted at that level while the tissue above and below expands freely, creating the two-tier profile. The same constriction of hollow viscera at a defect produces the collar sign.

Alternative names: Hump and band sign

Other associated named signs: Collar sign, dependent viscera sign, dangling diaphragm sign, and direct diaphragmatic discontinuity

References

1. Moliere S. Cottage loaf sign. Abdom Radiol (NY). 2017;42(11):2774-2775. PMID: 28528386.