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

الملخص EN

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.

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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/).