Spontaneous choroid plexus carcinoma in an albino rat

Neoplasms of the choroid plexus are very rare in the rat, and few cases have been described. We report on a spontaneously occurring choroid plexus carcinoma arising from the fourth ventricle in a 2-year-old female albino rat. The infiltrative growth was observed in the adjacent brain parenchyma, in the wall of the vessels of the circle of Willis, in the perivascular space of VIRCHOW and ROBIN and in the leptomeninges. Immunohistochemical investigations demonstrated positive staining for cytokeratin (Lu-5) indicating that choroid plexus tumors in the rat express epithelial differentiation. The diagnosis was made on the basis of microscopical and immunohistochemical findings.