Differences in Fine Mucosal Structure between Superficial Spreading Carcinoma and Non‐neoplastic Bile Duct Mucosa Detected by Percutaneous Transhepatic Cholangioscopy

Abstract

Abstract: Papillogranular mucosa is reportedly characteristic of superficial spreading bile duct carcinoma, but may also be seen in non‐neoplastic ductal tissue. This study was designed to clarify differences between these conditions by examining fine mucosal structure with percutaneous transhepatic cholangioscopy (PTCS) and methylene blue (MB) staining. Sixty‐three patients with malignant bile duct stenoses and 11 with benign bile duct disorders were examined by PTCS and the relationship between fine mucosal structure and histology was defined using endoscopic photographs and biopsy samples. Papillogranular mucosal samples contained superficial spreading carcinoma significantly more often than smooth mucosal samples (p<0.0001). Papillogranular mucosa was classified by fine structure into four types : regular papillogranular, nodular, finely reticulogranular and highly papillary. The latter three types were associated with superficial spreading carcinoma significantly more often than with non‐neoplastic mucosa (p<0.05). However, regular papillogranular mucosa was associated with both neoplastic and non‐neoplastic tissue. All papillogranular mucosal samples not stained with MB contained superficial spreading carcinoma. In 19% of papillogranular mucosa samples fine mucosal structure was identified by routine observation, while in 84% fine structure was determined by a combination of routine observation and MB staining. In conclusion, nodular, finely reticulogranular and highly papillary forms of papillogranular mucosa, as well as papillogranular mucosa which does not stain with MB, are characteristic of superficial spreading carcinoma. The combination of routine observation and MB staining is useful for analyzing the fine mucosal structure of papillogranular mucosa. However, meticulous observation is needed to diagnose superficial spreading carcinoma in regular papillogranular mucosa.