Quality assurance of pathology laboratories: analysis of histopathological diagnosis of endoscopical biopsies from lower alimentary tract based on specimen types

As a part of the internal quality assurance in the pathology laboratories, we focused on the diagnosis of biopsies from the lower alimentary tract, and investigated the number of independent lesions contributing the specimens, biopsy pieces, and paraffin blocks prepared in each pathological examination, from the standpoint of the types of biopsy procedures employed. In addition, we compared those of pre- and post-operative diagnoses, and examined the adequacy in the cases with repeated biopsies. Regarding the procedures, polypectomy and EMR (endoscopical mucosal resection) accounted for more than 60% of all the specimens handled during the study period. Most of the specimens taken by polypectomy or EMR were derived from neoplastic conditions, and roughly 40% of them were from malignancies including borderline lesions in a narrow sense. The examination of the surgically resected specimens confirmed a hundred percent accuracy ratio of the diagnosis on the biopsy specimens. Three cases (7.1%) out of 42 malignancies resected needed repeated biopsies in preoperative confirmation of malignancy, while the remainder (92.9%) had been diagnosed at the initial biopsy. The result disclosed that biopsies possessing both diagnostic and therapeutic value (polypectomy and EMR) are apparently increased in the field of lower alimentary tract, and the difficulty and efforts required for diagnosis are quite different and depend on the biopsy procedures employed.