Morphological Characteristics of Human Extrahepatic Bile Duct Carcinoma

Abstract

The number of surgically resected cases of extrahepatic bile duct cancers has been increased because of the recent advances in imaging diagnoses and operative procedures. However, morphological characteristics of the extrahepatic bile duct cancers have not yet been defined. In this study, we reviewed 102 surgically resected cases for clarifying growth and invasion of the extrahepatic bile duct cancer. We designated as cancer cancers limited to the mucosa or invading as far as the fibromuscular layer (smooth muscle layer), i.e., Tis or Tl cancers. Approximately 12.7% (13/102) of the cases were pTis or pT1 cancers (pathologic stage of Tis or T1), which were categorized as early cancer. Only 15.4% (2/13) of the early cancers showed vascular/perineural invasion and/or lymph node metastasis. In contrast, the majority (87.3%) of the cases was pT2-3 cancers, and very frequently showed vascular/perineural invasion and/or lymph node metastasis. Desmin immunostaining was very useful for recognizing thin muscle layer, and should be performed for pathological diagnosis of early extrahepatic bile duct cancers.