Renal carcinoid tumor: An immunohistochemical and molecular genetic study of four cases.

Few genetic studies of renal carcinoid tumor have been conducted thus far. We performed immunohistochemical and genetic examinations on four renal carcinoid tumors. Histologically, the tumors consisted of neoplastic cells with round to oval nuclei. Various growth patterns such as tightly packed cords and trabeculae, ribbon-like, trabecular, sheet-like or solid growth were observed. Nuclear chromatin showed a coarse and granular pattern. Immunohistochemically, tumors were positive for chromogranin A and synaptophysin. In the fluorescence in situ hybridization study, three of four tumors revealed monosomy of chromosome 3 (D3Z1), but one tumor showed monosomy of chromosome 13 (D13S319/13q34). Using PCR amplification and fragment analysis of three microsatellite markers (D3S1300, D3S666 and D3S1768) of chromosome arm 3p, one tumor showed loss of heterozygosity at D3S1300 and D3S1768, one tumor was not informative and the analysis of two tumors failed due to low DNA quality. In three cases, the VHL gene status was tested. Two tumors showed wild-type, but the analysis of one tumor failed to provide adequate results. In conclusion, we suggest that the abnormality of chromosome 3 is involved in the pathogenesis of renal carcinoid tumor.