The Epithelioid Variant of Angiomyolipoma in Kidney Expresses a Higher Level of Epidermal Growth Factor Receptor Than Its Conventional Type

Frank Chen, MD, PhD, David G. Hicks, MD, Christopher A. D’Angelis, MD, PhD, Haiying Chen, MD, Sheila Sait, PhD, Shaozeng Zhang, MD, PhD


The epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase that plays an important role in tumor growth, invasion and metastasis.  EGFR Positive immunoreactivity ranged from focal to diffuse in overexpression has been shown in many different tumors and multiple EGFR-targeted therapies are currently being investigated.  Renal epithelioid angiomyolipoma (epiAML) is an aggressive and potentially malignant variant of conventional angiomyolipoma (cAML).  Currently, the status of EGFR expression in epiAML is unknown.  We compared EGFR protein expression, as well as expression levels of several other tumor regulatory proteins including c-Kit, p53, alpha-catenin, beta-catenin and osteopontin in 6 cases of cAML and 10 cases of epiAML by semiquantitative immunohistochemistry (IHC).  EGFR gene amplification was analyzed by fluorescent in situ hybridization (FISH).  Within epiAML, EGFR immunostaining was significantly higher when compared to cAML (90% vs. 16.7%, p<0.01). epiAML, whereas no diffuse reactivity was found in cAML. EGFR gene amplification was not identified in either cAML or epiAML as illustrated by FISH.  Expression levels of c-Kit, osteopontin, p53, alpha-catenin

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