Histologic and Cytologic Diagnosis
Safe, minimally invasive techniques have been developed to definitively diagnose most digestive disorders, including the acquisition of cytologic or histologic specimens. This has been particularly important in malignant disease, where it is rarely, if ever, acceptable to consider treatment without first making a “tissue diagnosis.” In many more cases, cytology or pathology obtained by endoscopy can exclude a malignancy or diagnose a malignancy that does not require surgical intervention (e.g., gastric mucosa-associated lymphoid tissue [MALT] lymphomas, which are treated with antibiotics; malignancies that are diffusely metastatic and therefore beyond the benefit of surgery).
In many situations, highly accurate photo documentation may be a most valuable tool in making the diagnosis and guiding therapy. Much more often, however, biopsies are essential, even at times when the gross appearance is normal. Common examples of this in the upper gastrointestinal tract include eosinophilic esophagitis and celiac disease. Histology can also determine the cause of what may appear to be mild nonspecific erythema to reveal that it is due to an infection or Crohn disease. Histologic specimens obtained by endoscopic biopsies or cytologic specimens provided by brushes or fine-needle aspiration provide the clinician with definitive data with which an effective therapeutic strategy can be designed.
When receiving the results of a procedure, the ordering clinician should clarify whether biopsies or cytologic specimens were taken and the number of specimens taken. Providing the pathologist with a sufficient number of specimens to make a definitive diagnosis is a key quality metric. It is rarely, if ever, appropriate to take fewer than three specimens; taking this number does not increase the number of passes of the forceps (time) needed or the expense of the procedure. Endoscopists should also be adept at directing the biopsy forceps. Receiving an endoscopic report with photo documentation of an abnormality but with a pathology report that is read as normal should raise concern. The specimen should be taken with an optimal orientation. Taking biopsies tangentially to the orientation of the mucosa makes it difficult to provide a definitive and accurate diagnosis. Orientation is particularly important in the duodenum, where the biopsy should be obtained across a fold (plicae circulares) and perpendicular to the mucosa to accurately assess villous height and crypt depth, as is critical in assessing the diagnosis and severity of small intestinal mucosal diseases such as celiac disease.
Most exfoliated cytologic specimens are obtained by endoscopically guided brush cytologic procedures or interventional radiology experts. Abrasive brush devices for obtaining tissue for cytologic diagnoses, including an intraesophageal brush, have been proposed as a less invasive means of diagnosing esophageal disorders. Although the risk is lesser than with endoscopy, the procedure rarely provides definitive data for treatment and management. Potential limitations of guided fineneedle aspirations, whether obtained by EUS or radiology, include the risk of discomfort or bleeding; even multiple passages of the needle may not provide adequate cellular data. The risk of inadequate cellular data can be reduced by having a cytology expert in the procedure room to assess the quality of such specimens.
The problem of being able to provide definitive histologic or cytologic information for guiding treatment occurs all too commonly with the myriad of functional gastrointestinal disorders for which no histologic or cytologic specimen can provide a definitive diagnosis. These disorders are particularly challenging because they are common, lead to substantial degradation in the quality of life, and lead to a loss of productivity and success at school or work, but they almost never lead to serious complications or shortening of the life span. The astute clinician must use judgment based on the risk of finding an alternative diagnosis, particularly a life-threatening disease, to determine whether the taking of endoscopic photographs or histologic or cytologic specimens is warranted. To aid in this decision, various alarm signs and symptoms have been identified for most symptom complexes. These include symptoms that persist after effective therapy or that interrupt sleep; age over 45 years; the presence of fever, weight loss, nausea and vomiting, or anemia; or gross blood loss. Experts have also identified a number of criteria by which a diagnosis of a functional disorder can be made without ordering unnecessary testing, most notably the ROME criteria. Although they are not without controversy, such approaches provide a means by which excessive endoscopic and radiologic testing can be minimized.