Cytogenetics, immunostaining for fibroblast growth factors, p53 sequencing, and clinical features of two cases of cystosarcoma phyllodes

Background: We present cytogenetics and fibroblast growth factor immunohist ochemistry in one case of cystosarcoma phyllodes with localized disease and one with metastatic spread. The p53 gene was sequenced in the malignant ca se. Materials and Results: Karyotype analysis used trypsin-Giemsa banding. Immu nohistochemistry of FGF1, FGF2, FGFR1 and p53 used avidin-biotin detection of the primary antibody. One case had a mosaic female karyotype and three c lones: one normal, one with trisomy 7, and one with both trisomy 5 and a re arranged chromosome 1. In the second case, a resected pulmonary metastasis had the karyotype 43-47, XX, +mar1, +mar2[6]/43-46, XX, +del(7)(p10)[3], +m ar2[1][cp3]/46, XX[10]. These tumors expressed FGF1, FGF2, and FGFR1. The m alignant case showed immunostaining for p53 protein, but a wild-type gene s equence. Conclusion: The karyotype of cystosarcoma phyllodes is complex, with wide c ase-to-case variation. These tumors express members of the FGF family. Meta static behavior can occur in the presence of a wild-type p53 gene.