My approach to bowel ischaemia.

Resections of ischaemic bowel are one of the most common pathology specimens yet are often viewed as unappealing and diagnostically unrewarding. This article serves to dispel both misconceptions. It also provides guidance on how clinical information, macroscopic handling and microscopic assessment-and especially the interlinking of all three-can maximise the diagnostic yield of these specimens. This diagnostic process requires recognition of the wide range of causes of intestinal ischaemia, including several more recently described entities. Pathologists should also be aware of when and why such causes cannot be discerned from a resected specimen and of how certain artefacts or differential diagnoses can mimic ischaemia.

How many serial sections are needed to detect apoptosis in endoscopic biopsies with gastrointestinal graft versus host disease?

AIMS: The hallmark histological feature of acute gastrointestinal graft versus host disease (GI GVHD) is epithelial apoptosis. This is the first formal evaluation of how many serial sections are required to consistently detect apoptotic bodies in endoscopic biopsies from various GI locations in patients with clinically validated GI GVHD. METHODS, RESULTS AND CONCLUSIONS: Assessment of 1008 serial sections showed that apoptotic bodies are uniformly distributed among such sections of gastric, duodenal and colorectal biopsies from these patients. Assessment of 59 further biopsies showed that assessing 12 serial sections should suffice to detect GVHD in gastric, duodenal and colorectal biopsies using thresholds of one apoptotic body per biopsy fragment or one apoptotic body per 4 mm2. Assessing 12 serial sections should also suffice to detect GVHD in duodenal and colorectal biopsies using the threshold of 6 apoptotic bodies per 10 contiguous crypts, but it remains uncertain whether this assessment and threshold can be applied to gastric biopsies.