Histopathology: how to get the best from gastrointestinal biopsies

Sampling of the gastrointestinal tract by endoscopic or full thickness (open abdominal surgical) biopsy is an invaluable tool in the diagnosis and management of gastrointestinal disease in companion animals. However, the collection of samples requires considerable clinical and surgical skill and a general anaesthetic is needed for the animal, often at significant expense to the owner. For these reasons, it is important to maximise the value of this process by careful case selection, acquisition of high quality biopsy specimens and a clear understanding of both the value and limitations of histological examination. Furthermore, close collaboration between pathologist and clinician is essential, particularly when the histology alone does not provide a definitive diagnosis and further clinical correlation and/or testing is required to obtain a complete picture of the disease process (Elwood, 2005).

Histopathology can provide valuable information to be applied in the management and treatment of gastrointestinal disease, by helping practitioners reach a specific diagnosis or by guiding them in their approach to further investigation and treatment (Stidworthy and Priestnall, 2011). Reaching a definitive diagnosis through histopathology depends on multiple factors, including appropriate case selection, clinical sampling, tissue preparation, and the provision of a relevant and correct clinical history. Nevertheless, each organ system in the body, including the gastrointestinal tract, has a limited repertoire of responses and there will always be cases that present with findings that are not aetiologically-specific, even when sampling and submission have been performed optimally. Therefore, it is important that practitioners and clients understand both the value and limitations of histopathology. The histopathological findings should always be interpreted within the context of the clinical presentation, results of laboratory tests, other diagnostic data and the response to any treatment. This is particularly true for inflammatory conditions of the gastrointestinal tract. The relationship between clinician and pathologist should be open and bidirectional; if the histopathological diagnosis does not fit the patient's clinical presentation, the clinician should not hesitate to contact the pathologist to discuss the case further.