Isolated Proximal Black Esophagus in a COVID-19 Patient.

Black esophagus or acute esophageal necrosis (AEN) is a rare cause of upper gastrointestinal (UGI) bleeding usually involving distal esophagus. Proximal esophageal involvement is quite rare. We present an 86-year-old female with active coronavirus disease 2019 (COVID-19) infection who came in with newly diagnosed atrial fibrillation and was started on anticoagulation.

Novel Case Report: A Previously Reported, but Pathophysiologically Unexplained, Association Between Collagenous Colitis and Protein-Losing Enteropathy May Be Explained by an Undetected Link with Collagenous Duodenitis.

Collagenous colitis (CC) is associated with non-bloody, watery diarrhea, which is pathophysiologically reasonable because normal colonic absorption (or excretion) of water and electrolytes can be blocked by the abnormally thick collagen layer in CC. However, CC has also been associated with six previous cases of protein-losing enteropathy (PLE), with no pathophysiologic explanation. The colon does not normally absorb (or excrete) amino acids/proteins, which is primarily the function of the small bowel.