Fig. 5From: Occult mucin-producing cholangiocarcinoma in situ: a rare clinical case with difficult tumour stagingHistological findings. Papillary projection, which was formed of atypical epithelial cells with multilayering nuclei and moderately increased N/C ratio is present in the S1 cyst. Because of the marked papillary structural atypia, despite moderate cellular atypia, the diagnosis of papillary adenocarcinoma in situ was madeBack to article page