Mesectodermal leiomyosarcoma of the ciliary body.

We report a case of low-grade mesectodermal leiomyosarcoma of the ciliary body, an extremely rare tumor of neural crest origin, occurring in a 12-year-old boy. MR imaging showed a well-marginated, ovoid soft tissue mass at the right temporal ciliary body, accompanied by total retinal detachment. The mass was slightly hyperintense relative to contralateral vitreous on T1-weighted images and markedly hypointense on T2-weighted images and enhanced very well. Initial biopsy of the mass suggested a peripheral nerve sheath tumor. The mass grew rapidly after biopsy, and enucleation was performed. The final diagnosis based on histology and immunohistochemistry was a low-grade mesectodermal leiomyosarcoma. To our knowledge, this is the first reported case of a malignant form of mesectodermal leiomyoma of the ciliary body.