EGFR-expression in pulmonary neuroendocrine cell hyperplasia

15 cases of pulmonary neuroendocrine cell hyperplasia (carcinoid-tumorlets, diffuse idiopathic pulmonary neuroendocrine cell hyperplasia/DIPNECH) and 20 neuroendocrine pulmonary tumors (10 carcinoid tumors, 5 large cell neuroendocrine, and 5 small cell neuroendocrine lung carcinomas) were immunohistochemically analyzed for the expression of epidermal growth factor receptor (EGFR, = HER-1). All cases of neuroendocrine cell hyperplasia exhibited a maximum EGFR expression (score 3 in 100% of cells) showing predominantly membranous, partly cytoplasmic staining. 4 ot the 10 carcinoid tumors were strongly positive for EGFR, whereas the other 6 were EGFR-negative. A total of 90% of large cell neuroendocrine and small cell neuroendocrine carcinomas were negative for EGFR. Overexpression of EGFR in pulmonary neuroendocrine cell hyperplasia might be significant for the pathogenesis of these lesions. As DIPNECH is characterized by clinical signs and symptoms including mild cough and obstructive functional impairment, a specific antagonistic therapeutic trial could aim at blocking EGFR/HER-1 or its subsequent signal transduction pathway.