Mesectodermal Leiomyosarcoma of the Ciliary Body

Low-grade mesectodermal leiomyosarcoma of the ciliary body in a 12-year-old boy.

A and B, MR images obtained before biopsy demonstrate a well-marginated, ovoid soft tissue mass (white arrows) at the temporal aspect of the right ciliary body, accompanied by a large amount of subretinal fluid (black arrows) caused by retinal detachment. Compared with contralateral vitreous, the signal intensity of the mass was slightly hyperintense on T1-weighted (not shown) and markedly hypointense on T2-weighted (A) images, whereas that of subretinal fluid was markedly hyperintense on T1-weighted and slightly hypointense on T2-weighted images. The mass enhanced very well, whereas the subretinal fluid did not (B). Note focal hyperintensity within the mass on the T2-weighted image (arrowhead in A), which suggests cystic or necrotic change.

C, Axial T2-weighted MR image obtained 10 days after biopsy shows the deformed, macrophthalmic right eye whose anterolateral coat is pushed outward in association with a total retinal detachment. There is a relatively well-marginated, crescentic, markedly hypointense soft tissue mass (arrows) along this protruding portion of the ocular coat. The mass was slightly hyperintense to contralateral vitreous on T1-weighted images and enhanced well (not shown), as same as the original ciliary body mass shown on the MR images obtained before biopsy. The boundary of the uveoscleral coat in the vicinity of the mass is partly indistinct (arrowheads), which indicates tumoral infiltration. Subretinal fluid containing fluid-fluid level, which shows mixed isointensity and hyperintensity to contralateral vitreous on this T2-weighted image, demonstrated slight hyperintensity on T1-weighted images (not shown), representing various stages of subacute hemorrhage. Also noted was the lens subluxated laterally.

D, Macroscopic view of horizontal section of the enucleated right eye shows marked outward protrusion of the anterolateral ocular coat where a relatively well defined, crescentic, firm, grayish brown mass is located (arrows). It is firmly attached to the overlying sclera (arrowheads). There is a total retinal detachment and associated subretinal fluid containing brownish gray gelatinous material and blood clot.

E, Photomicrograph shows that the tumor is composed of sheets of large polygonal cells that have large round to oval hyperchromatic nuclei, abundant eosinophilic cytoplasm with indistinct borders, and slender cellular processes blending into a fibrillary background (hematoxylin-eosin stain, original magnification ×100). F, High-magnification photomicrograph shows moderate cellular atypia and several mitotic figures (arrows) among the tumor cells (hematoxylin-eosin stain, original magnification ×400).