Pediatric adrenocortical neoplasms: immunohistochemical expression of p57 identifies loss of heterozygosity and abnormal imprinting of the 11p15.5.

Abstract

Diagnosis of adrenocortical neoplasms (ACN), in pediatric age, is based on Wieneke criteria. The p57, a cyclin-dependent kinase inhibitor, acts to negatively regulate cell proliferation and is frequently found dysregulated in cancer. The identification of loss of heterozygosity (LOH) of 11p15, containing the p57 gene, could be a tool for differential diagnosis of benign and malignant ACN. Immunohistochemistry with anti-p57 and microsatellite markers analysis of 11p15 region to value LOH were made in both ACN and surrounded normal adrenal cortex. Nine ACN, two clinically benign, two uncertain, and five malignant, were diagnosed. Positive p57 cells were evident in normal adrenal cortex and in one histologically benign ACN. A low/absent expression of p57 was documented in eight ACN independently from the classification on the basis of pathological and clinical criteria. Microsatellite marker analysis confirmed the LOH of 11p15 region in the same ACN. LOH of 11p15 has a high prognostic value suggesting the p57 gene is important in ACN pathogenesis. Immunohistochemistry for p57 is a simple and cheap tool that can be used to quickly identify LOH of 11p15 in ACN.