Pathology of the Head and Neck

298 M.R. Canninga-Van Dijk1010.4.4.3 Phtisis BulbiA long period of time after a trauma or an inflammatorydisease, the total eye becomes atrophic. As long as choroidaland retinal anatomy are preserved, this is calledatrophia bulbi. As soon as disorganisation of choroideaand retina occurs, it is called phtisis bulbi. A reactive cellproliferation dominates the histology. This proliferationcan be fibroblastic (trauma of cornea, sclera, choroideaor iris), or glial (retinal damage). Also, proliferation ofretinal pigment epithelium or ciliary body epitheliumcan be seen. The optic nerve is usually completely atrophic.10.4.4.4 Retinal Vascular DiseaseLoss of vision caused by ischaemic disease of the retinais common. It can be due to several different vasculardisorders. Most frequently it is caused by central retinalvein occlusion, diabetes, or occlusion of a branch vein.More rare are vasculitis, retinopathy of prematurity,radiation retinopathy, central retinal artery occlusion,hypertension and disseminated intravascular coagulopathy.Occlusion of an artery causes white infarction,while occlusion of veins leads to haemorrhagic infarction.The ischaemic area can vary between focal (occlusionof branch vessels), segmental, or total (occlusion ofthe central retinal vein or artery). Ischaemia of the retinawith damage of retinal vasculature shows leakage ofred cells, followed by neovascularisation and formationof microaneurysms. In the final stage, secondary angleclosure glaucoma can develop with corneal ulcerationand cataract formation, resulting in a not only blind butalso painful eye. The globes are often enucleated to relievepain. At macroscopic examination an ectropion ofthe iris pigment epithelium, caused by the neovascularmembrane on the iris surface is visible (but only if thecornea is transparent). At microscopic examination, theproliferation of endothelial cells in the retina is the moststriking finding. Sometimes CD31 and GFAP stainingare necessary to differentiate the vascular proliferationfrom reactive gliosis.10.4.4.5 Retinal DetachmentSeveral degenerative conditions predispose to retinal detachment.The separation between the neural retina andthe retinal pigment epithelium can be caused by traction,exudate, or by so-called rhegmatogenous detachment.Traction detachment occurs when the vitreousshows fibrosis or gliosis, following trauma or by neovascularisation.Accumulation of fluid between the layersof the retina is called exudative detachment. It can becaused by processes with excessive permeability of retinalor choroidal vessels, like inflammatory or neoplasticdisorders. In rhegmatogenous detachment, passage offluid from the vitreous cavity to the subretinal space ispresent. It occurs through a hole in the retina, caused bydegeneration or a minor trauma. Enucleated eyes withretinal detachment usually show many signs of previoussurgical intervention. The most important informationfor the surgeons is whether the retina survived the separationand reattachment or not and if a reason for surgicalfailure can be found.10.4.4.6 Retinitis PigmentosaRetinitis pigmentosa presents in early life with nightblindness and a progressive reduction in the visual field,starting at the periphery. Retinal architecture remainsbest preserved at the macula, so the patient ends up withtunnel vision. Different chromosomal abnormalities havebeen found in patients with retinitis pigmentosa. Microscopicexamination shows retinal atrophy with proliferationof Müller cells (retinal supporting cells at the outerside of the retina) replacing the outer nuclear layer. Theretinal pigment epithelium proliferates and can surroundsmall hyalinised vessels in the retina. A marked variationin the extent of retinal degeneration can be seen in tworelatives with retinitis pigmentosa [117].10.4.5 Tumoursand Tumour-Like Conditions10.4.5.1 MelanocyticMelanocytes in the uveal tract can give rise to both benignand malignant tumours. Racial differences mayreflect themselves by variance in prominence and enlargementof melanocytes in the choroid, ciliary bodyand iris. It is very important for pathologists to be awareof these differences.10.4.5.1.1 NaevusICD-O:8720/0Iris naevi present as pigmented macular lesions, arevery slowly progressive, and often completely static overyears. When the clinical presentation is not suspicious,in most cases the lesion will not be excised. For that reason,naevi of the uveal tract are most commonly incidentalfindings. Histology shows a symmetrical lesion,located in the anterior part of the iris stroma, and usuallycomposed of small spindle cells with small, uniformnuclei. Large nucleoli and especially mitotic figures indicatea suspected malignant melanoma.