Immunohistochemical basis for adjuvant anti-angiogenic targeted therapy for renal carcinoid: Initial case report

ObjectivesTo evaluate the immunohistochemical profile of a carcinoid (low grade neuroendocrine tumor of the kidney) from a patient with lymph node positive disease who remains disease free for 31 months after radical nephrectomy, lymph node dissection, and adjuvant therapy with sunitinib malate.MethodsImmunohistochemical staining was performed for chromogranin, synaptophysin, CD31, VEGF, HIF-1α, HIF-2, and Glut-1. Staining was evaluated in 3 high-power fields and samples scored as strongly positive (3+), moderately positive (2+), weakly positive (1+), or negative (0). A clear cell renal cell carcinoma was used as positive control.ResultsImmunohistochemical staining was strongly positive VEGF, weak to moderately positive for HIF-2, and negative for HIF-1α and Glut-1.ConclusionsOur case of primary renal carcinoid stained intensely for VEGF and HIF-2, consistent with a VHL-HIF1-HIF2-Glut1 independent pathway for VEGF activation. These data suggest that like other neuroendocrine tumors, primary renal carcinoid is a potential target for anti-angiogenic therapy with sunitinib.