A CASE OF INFLAMMATORY PSEUDOTUMOR OF THE COMMON BILE-DUCT

Inflammatory pseudotumour of the common bile duct (CBD) is extremely r are. A 58-year-old Japanese female without choledocolithiasis underwen t pancreatico-duodenectomy for constriction of the middle lower region of the CBD. A submucosal tumour protruding into the CBD, was histolog ically inflammatory consisting of fibroblastic cells, collagen fibres and myxoid stroma with chronic inflammatory cells. This lesion was sur rounded by an irregular fibrosclerosing lesion with obliterative phleb itis which involved the neighbouring pancreas and lymph nodes. Clonal analysis of the tumour by polymerase chain reaction analysis of X chro mosome inactivation patterns, confirmed the polyclonal nature of the l esion. Immunohistochemically, the fibroblastic cells in both lesions h ad the same phenotype [vimentin (+), desmin (-), muscle-specific actin (-) and CD34 (+)] suggesting that these lesions with different histol ogical features represent zonation of the same inflammatory process. T he outer lesion extended irregularly into adjacent pancreatic tissue a nd lymph nodes. This fact made it difficult to differentiate this from a malignant lesion, even if frozen sections contained no atypical cel ls.