MACROSCOPIC DESCRIPTION: 

A soft white core biopsy 18 mm long and 1 mm in diameter.

MICROSCOPIC DESCRIPTION:

Sections show a core paucicellular fibrous tissue composed of bundles of collagen interspersed with bland stellate fibroblasts and a few small vessels. In immunostains, there is strong nuclear staining for beta-catenin.

DIAGNOSIS: Core biopsy of abdominal lesion: Fibrous tissue suggestive of a desmoid tumor.