Solitary fibrous tumors of the pleura represent a rare clinicopathological entity: 456 cases only have been reported since 1991. A interesting case of solitary fibrous tumor of the pleura is described here, because it turned up in a female patient followed up for a bilateral breast cancer and so with the exact determination of the period of beginning. The complex morphological picture is illustrated in relation to other cases reported in the literature. Immunohistochemical results are stressed, particularly as regards the coexpression of vimentin and desmin without necrosis and the low number of mitosis. As there are no criteria to determine the possible aggressive or malignant behaviour of the tumor, surgical resection of the lesion is indispensable both to resolve the diagnosis and to carry out the only proposable therapy.