HYALINIZING SPINDLE-CELL TUMORS WITH GIANT ROSETTE-LIKE STRUCTURES

We report two cases of hyalinizing spindle cell tumors with giant rose ttes arising in the pararectal space and soft tissues of the wrist in a 46-year-old man and 22-year-old-woman, respectively. Microscopically , the tumors exhibited a varied morphology, including hyalinizing hypo cellular and cellular fibromatosis-like areas. The most striking morph ologic feature was the formation of giant rosette like structures with collagen cores scattered throughout the tumors. Most of the tumor spi ndle cells were diffusely immunoreactive for lysozyme, CD-68, factor X III and vimentin. Reactivity for smooth muscle actin, desmin and S-100 protein was not found. Ultrastructural examination of the rosettes in one case only showed normal native collagen.