Evaluation of the Cell Block Method Using Overnight-Stored Bile for Malignant Biliary Stricture Diagnosis

SIMPLE SUMMARY: Collecting specimens for pathological diagnosis of malignant biliary stricture (MBS) is not easy. This study shows that cell block (CB) of overnight-stored bile is useful for pathological diagnosis of MBS. Cancer detectability using the CB method (62.2%) is superior to that using cytology (37.8%). When the CB method is combined with biopsy, the cancer detectability (75.6%) and accuracy rates (81.4%) are increased. In addition, immunohistochemistry can be applied to the CB method when encountering difficult cases for pathological diagnosis. The CB method utilizing overnight-stored bile can be routinely used for detecting MBS in local hospitals. ABSTRACT: The specimen collection and subsequent pathological diagnosis of malignant biliary stricture (MBS) are difficult. This study aimed to determine whether the cell block (CB) method using overnight-stored bile is useful in the diagnosis of MBS. This trial was a single-arm prospective study involving a total of 59 patients with suspected MBS. The primary endpoint was cancer detectability and accuracy using the CB method, and a comparison with the detectability and accuracy achieved with bile cytology was made. The immunohistochemical sensitivity for maspin and p53 was also investigated in the CB and surgical specimens. We were able to collect bile from all 59 patients, and 45 of these patients were clinically diagnosed with MBS. The cancer detectability using the CB method (62.2%) was significantly higher than that using cytology (37.8%) (p = 0.0344). When CB was combined with biopsy, the rates of cancer detectability (75.6%) and accuracy (81.4%) increased. In eight patients who received surgical therapy, maspin- and p53-immunohistochemistry was applied to the surgical and CB specimens, and cancer cells in both specimens showed positive cytoplasmic and nuclear staining for maspin and nuclear staining for p53. The CB method is, thus, useful for detecting malignancy (UMIN000034707).