Eosinophilic dysplasia of the gallbladder: a hitherto undescribed variant identified in association with a "porcelain" gallbladder

Non-mass forming, neoplastic intraepithelial proliferations (dysplasia) represent the most well-accepted precursor lesions to gallbladder adenocarcinomas. They are typically small, localized, grossly unrecognizable lesions that have been identified in the epithelium adjacent to up to 79% of gallbladder adenocarcinomas. Morphologic variants that have been reported include flat, micropapillary, papillary and cribriform. We have recently encountered a morphologically distinctive, previously unreported lesion to which we have applied the designation eosinophilic dysplasia. This lesion was identified in a gallbladder with diffuse mural fibrosis and calcification (porcelain gallbladder). The dysplastic focus was confined to one tissue section, and was comprised of a localized true papilla [i.e with a fibrovascular core], measuring approximately 1.2 mm in greatest dimension and an adjacent, flat, 7-cell epithelial segment. These foci were lined by cells displaying significant nuclear enlargement [1.5–4 times the adjacent benign cells], nuclear pleomorphism, occasional multinucleation, hyperchromasia and nuclear membrane irregularities. Nucleoli were present but inconspicuous. These cells also showed voluminous eosinophilic to granular cytoplasm, such that the overall nuclear-to-cytoplasmic ratio was generally not increased. The cells displayed diffuse and marked nuclear immunoreactivity for p53, and approximately 70% of the cells showed nuclear positivity for Ki-67. The cells were also positive for cytokeratin 7 and were entirely negative for carcinoembryonic antigen (CEA) and chromogranin A. The cells of the adjacent normal epithelium were positive for cytokeratin 7 and CEA, negative for p53 and chromogranin A and showed a Ki-67 labeling index of <10%. Marked overexpression of the p53 protein as well as its high proliferative index are strong arguments in favor of the dysplastic nature of this lesion. However, further studies are required to elucidate its true clinical significance and to determine whether or not its association with a porcelain gallbladder, as noted herein, is entirely fortuitous. However, such studies can only be performed with an increased recognition by practitioners of this distinctive variant.