Contributed by Diana N. Ionescu, MD, Johnathan A. Engh, MD and Charleen T Chu, MD, PhD.
Published on line in May, 2004
CLINICAL HISTORY AND RADIOGRAPHIC FINDINGS:
A toddler presents with increasing proptosis, buphthalmos and decreased visual acuity in the left eye. The patient also has severe left-sided periorbital pain. Shortly after birth, she was diagnosed with congenital glaucoma of the left eye. Her condition has been refractory to multiple medications. Two surgical procedures, a trabeculotomy and a trabeculectomy, have also failed to control her elevated intraocular pressure. The patient has café au lait spots, axillary and inguinal freckling, sphenoid wing dysplasia and bilateral Lisch nodules. There is no family history of neurofibromatosis. How does this information influence your clinical differential diagnosis? Due to her worsening vision, pain and cosmetic deformity, magnetic resonance imaging (MRI) of the left orbit is performed.
MRI scan of the left orbit demonstrates diffuse enlargement of the left globe (Figure A and B). Masses are noted in the superior aspect of the left orbit (Figure C), distending the extraocular muscles. The tumor enhances and extends posteriorly and inferiorly into the left cavernous sinus (Figure D). Marked unilateral proptosis of the left orbit is clearly demonstrated (Figure A).
Due to the worsening visual acuity, pain and cosmetic deformity caused by the lesions in the left orbit, the patient is taken to the operating room for enucleation of the left eye with resection of the intraorbital masses.
Submitted for pathologic examination is an enucleation specimen identified as the left eyeball. How do you correctly identify and orient an eyeball specimen? The anterior-posterior diameter measures 29 mm, the horizontal 26 mm and the vertical 25 mm. What are the normal dimensions of a human eyeball? The cornea is clear. The iris is brown and displays a 4 mm papillary opening that is displaced toward 2:00 (Figure 1). A 3 mm segment of optic nerve is attached to the eyeball, with a cross-sectional diameter of 2-2.5 mm. No opacities are identified upon transilumination of the eye. Why is translumination performed? The eyeball is transected in the horizontal plane. This reveals cloudiness of the posterior lens (Figure 2), and cupping of the optic nerve head (Figure 3 -arrow). The choroid is abnormally thick, displaying a homogeneous tan cut surface (Figure 4-arrows).
Also received labeled "orbit tumor" were multiple fragments of lobulated, translucent white-tan tissue, measuring 2.5 x 2.5 x 0.5 cm in aggregate (Figure 5).
Microscopic examination of the orbital soft tissue reveals expanded, disorganized nerve fascicles permeating extensively through orbital muscle tissue. The tumor (Figure 6) is characterized by loosely arranged spindle cells in a myxoid background. Neoplastic tissue is focally adherent to the outer surface of the optic nerve sheath, but the optic nerve itself is not involved. Trichrome stain highlights myelinated fibers clustered in the center of the nerve fascicle (Figure 7) that is confirmed by neurofilament immunohistochemistry (Figure 8). S-100 immunostain is positive in wavy, spindled cells within the nerve fascicles (Figure 9).
There is mild basilar edema of the corneal epithelium. The iris is adherent to the posterior cornea (peripheral anterior synechiae). The choroid and ciliary body are expanded by increased numbers of pigmented and nonpigmented spindle cells and pseudo-meissnerian corpuscles (Figure 10), which are S-100 immunoreactive. CD68 immunostain highlights a small cluster of macrophages in the anterior sclera, but does not stain the pseudo-sensory corpuscles. Neurofilament stain shows a spiral staining pattern within the pseudo-sensory corpuscles (Figure 11). There are also axonal structures unassociated with these corpuscles in the choroid and ciliary body (Figure 12), but not in the iris . There is a small plaque of HMB-45 immunoreactive spindle cells on the surface of the iris (Figure 13, H&E). The retina shows loss of ganglion cells. There is cupping of the optic nerve head (Figure 14). The lens shows changes of cataract. (Figure 15).