It's uncommon, but once in a while, blue nevi are encountered in colonic mucosa and present as dark patches. Case provided by Dr....

This epithelioid malignant peripheral nerve sheath tumor shows loss of INI1/SMARCB1, a feature of this type of neoplasm....

Autoimmune enteropathy pattern of injury. What is absent can be as important as what is present in gastrointestinal biopsies. Missing in...