Comparative immunohistochemical expression of b-catenin, egfr, erbb2, and p63 in adamantinomatous and papillary craniopharyngiomas

Craniopharyngiomas (CPs) are rare epithelial tumors located mainly in the sellar/ parasellar region. CPs have been classified into histopathologically, genetically, clinically and prognostically two distinctive subtypes: adamantinomatous and papillary variants. Aim: To determine the immunohistochemical expression of b-catenin, EGFR, ErbB2, and p63 in adamantinomatous and papillary CPs. Materials and methods: b-Catenin, EGFR, ErbB2, and p63 immunostaining was performed on paraffin embedded tissue sections of 25 CPs including 18 adamantinomatous craniopharyngioma (ACP) and 7 cases of papillary craniopharyngiomas (PCPs). Results: 17 cases (94%) of ACP exhibited strong nuclear/cytoplasmic expression of b-catenin. On the contrary, all cases of PCP showed exclusively membranous expression (P value < 0.0001). Regarding EGFR, 15 (83%) and 5 cases (71%) of APC and PCP respectively were positive. On the other hand, only 3 cases (17%) of APC and none of PCP exhibited positivity for ErbB2. p63 over-expression was observed in 16 cases of ACP (89%) and 6 cases of PCP (86%). However,the distribution of p63 staining was diffuse in ACP, while in PCP; the staining was mainly restricted to the basal cell layer. Conclusion: Nuclear accumulation of b-catenin is a diagnostic hallmark of the ACP and is very helpful in the differential diagnosis between both ACP and PCP in the setting of small biopsies. Moreover, the restricted nuclear b-catenin accumulation in the cohesive cell clusters within the whorl-like areas supports that aberrant b-catenin expression may play a role in the morphogenesis of ACP. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of National Cancer Institute, Cairo University. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).