Solitary fibrous tumor of the greater omentum in an inguinal hernia sac

A 40-year-old man visited our hospital in December 2008 complaining of a painless mass in the left inguinoscrotal area. The surface of the mass, expected to be a tumor, was smooth and mobile. Ultrasonography showed the tumor was separated from the same-side testis, and extended to the spermatic cord. Computed tomography (CT) revealed that the heterogeneous tumor extended to the spermatic cord, and that the left inguinal canal was dilated. We diagnosed him with a left spermatic cord tumor, and left ascensus orchiectomy was performed on February 5th, 2009. With regard to the operative findings, the tumor was located in the inguinal hernia sac and extended to the greater omentum, and was separated from the spermatic cord. Immunohistochemical examination showed positive reactivity for CD99 and vimentin; however, desmin, S100, and bcl-2 were negative. CD34 was positive only in a few tumor cells around the blood vessel. The final diagnosis was solitary fibrous tumor (SFT), although it was not a representative type, originating from the greater omentum, existing in an inguinal hernia sac. This is the first such case to be reported anywhere in the world. So, we describe this rare case.