A 57 year old man is seen in clinic for a chronic cough. Chest x-ray demonstrates a lung mass; bronchoscopy with bronchial lavage and biopsy reveals a tumor composed of small neoplastic cells with prominent crush aifact that do not stain with immunohistochemical stains for lymphocyte common antigen (LCA). Which of the following oncogenes has been associated with this tumor?

The presence of a lung mass suggests carcinoma. The small size of the neoplastic cells suggests that the tumor may be small cell carcinoma (oat cell carcinoma). The other possibility on morphologic grounds is lymphoma, but lymphoma can be excluded by the negative LCA study. The oncogene associated with small cell carcinoma of the lung is L-myc. bcl-2 is associated with follicular and undifferentiated lymphomas. erb-2 is associated with carcinomas of the breast, ovary, and stomach. N-myc is associated with neuroblastoma. Ref: Nason K.S., Maddaus M.A., Luketich J.D. (2010). Chapter 19. Chest Wall, Lung, Mediastinum, and Pleura. In F.C. Brunicardi, D.K. Andersen, T.R. Billiar, D.L. Dunn, J.G. Hunter, J.B. Matthews, R.E. Pollock (Eds), Schwaz's Principles of Surgery, 9e.