|Year : 2012 | Volume
| Issue : 1 | Page : 73-75
Intraocular osseous metaplasia
Archana C Buch, Yugam V Chopra, Pradeep S Jadhav, Pradhan M Pagaro
Department of Pathology, Pad. Dr. D. Y. Patil Medical College and Research Centre, Pimpri, Pune, Maharashtra, India
|Date of Web Publication||20-Jun-2012|
Archana C Buch
B 603, Gold Coast, Ivory Estates, Someshwarwadi, Pune - 411 008, Maharashtra
Heterotropic bone formation or intraocular osseous metaplasia is a rare finding. Trauma, chronic inflammation, and long-standing retinal detachment are some of the common etiological factors associated with the onset of intraocular ossification. We report a case of a 16-year-old girl with a history of blunt trauma 6 years back, who complained of right eye blindness. Right eye enucleation was done which on histopathological examination revealed pre-retinal lamellar bone with fatty marrow. We diagnosed her case as intraocular ossification in phthisis bulbi.
Keywords: Intraocular, osseous metaplasia, phthisis bulbi
|How to cite this article:|
Buch AC, Chopra YV, Jadhav PS, Pagaro PM. Intraocular osseous metaplasia. Med J DY Patil Univ 2012;5:73-5
| Introduction|| |
Heterotropic bone formation can occur in any tissue, but it is rarely found in the eyeball. According to the study of Finkelstein and Boniuk,  who examined 2486 enucleated eyes, intraocular ossification was found in only 119 cases (4.8%). Intraocular osseous metaplasia is known to occur in association with phthisis bulbi, long-standing retinal detachment, chronic inflammation, age-related macular degeneration, microphthalmos, buphthalmos, and trauma. ,, It is also seen with intraocular tumors such as choroidal hemangioma, choroidal osteoma, choroidal melanoma, and teratoma. Location of ossification can be subretinal (37.5%), preretinal (12.5%), or both (50%).  Both the locations represent different pathogenesis. We hereby present a rare case of preretinal intraoccular osseous metaplasia and discuss its pathogenesis.
| Case Report|| |
A 16-year-old female presented with complaints of inability to see from right eye since last 6 years. She had a past history of accidental trauma by fist of hand leading to acute red eye, which subsequently resulted in loss of vision. There was no significant personal and family history. General and systemic examinations were normal.
Ophthalmic examination of right eye revealed no perception of light and narrowing of interpalpebral fissure. Eye showed leucomatous opacity involving lower 1/3 rd of cornea with superficial and deep vascularization [Figure 1]a. Anterior chamber was deep. Iris showed iridodonesis with multiple patches of iris atrophy. Pupil was not reactive to direct and consensual light reflexes. Lens showed cataractous changes and fundus details were not well appreciated. Ophthalmic examination of left eye was normal with vision 6/6.
|Figure 1: (a) Right eye showing leucomatous opacity in the cornea, (b) Post surgical view of the right eye|
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Laboratory investigations revealed Hb 13 gm%, WBC 6100/mm 3 , Bleeding time 1'20", Clotting time 5', ECG was normal.
B scan examination of right eye revealed choroidal detachment with signs of choroidal calcification.
Right eye enucleation was done. An Artificial prosthesis was implanted after 6-8 weeks under general anesthesia [Figure 1]b.
The enucleated eye ball with optic nerve was sent for histopathological examination [Figure 2]a. Grossly, the specimen measured 2 cm × 1.8 cm × 1.5 cm. External surface revealed blackened cornea. The specimen was gritty to cut. Cut surface showed blackish brown areas. Microscopically, the ocular tissue showed degenerative changes with cholesterol clefts and giant cell reaction [Figure 2]b. The choroid and ciliary body appeared detached. The vitreous showed areas of hemorrhage. Few areas of ossification were seen in the preretinal region [Figure 2]c, d. Dystrophic calcification was seen at places where retina was detached. No inflammatory infiltrate was seen. The optic nerve appeared unremarkable and there was no evidence of malignancy.
|Figure 2: (a) Gross picture of enucleated eye, (b) Cholesterol clefts (H & E, 400×), (c) Preretinal osseous metaplasia (thin arrow) between choroid (arrowhead) and retina (thick arrow) (H&E, 100×), (d) Compact bone with fatty marrow (H&E, 400×)|
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| Discussion|| |
Heterotropic bone formation in the eyeball is a rare finding. The incidence varies from 5% to 18%.  Intraocular ossification has also been found in lens, retina, all parts of posterior segment, and the cyclitic membrane. The most frequent site is the sub-retinal region and the inner surface of choroids.  The location was pre-retinal in our case.
Monsalie et al. found that trauma was the leading etiological factor in the age group 10-50 years as seen in our case, whereas inflammation was the leading cause after 50 years of age. Intraocular ossification can show compact bone, spongy bone, or both.  Compact bone is encountered more frequently in post-traumatic cases, while spongy bone is encountered in post-inflammatory cases. We found compact bone in our case as it was following trauma. These findings support an interesting correlation between the type of bone and the etiological factors.
Heterotropic bone can be formed at the focus of dystrophic calcification. Long-standing calcification is said to be a necessary precursor to ossification.  Bone is usually formed in the eye at least 10 years after injury or diseases, but several cases have been reported in which the bone is formed in less than 2 years.  Although the stimulus for osteogenesis is still not well understood, we do know that bone formation requires precursor cells such as osteoblast which are derived either from the osteogenic precursor cell found in the marrow stroma or from the precursor cell found in the connective tissue framework of many tissues and in the circulating blood.  Suggested pathogenic mechanism of intraocular osseous metaplasia is vascular delivery of osteoblast to tissues with inherent high vascularity, such as choroid, or the transdifferentiation of the retinal pigment epithelial cells into fibrotic or osteoblastic phenotype seen in sub-retinal osseous metaplasia.  Recent studies have reported osseous metaplasia in pre-retinal membranes removed from eyes with rhegmatogeneous retinal detachment and proliferative vitreoretinopathy.  Pre-retinal osseous metaplasia could result from metaplasia of retinal pigment epithelial cells that migrate along the back surface of detached retina, through retinal breaks.  Retinal pigment epithelium is known to be a multipotential cell with the capacity to differentiate into a mesenchymal phenotype, including fibroblast and osteoblast. It is now suggested that intraocular ossification results from osteoblastic transformation of the retinal pigment epithelium.  This transformation requires an inducing agent which may be produced by trauma, inflammation, or anoxia subsequent to chronic retinal detachment. ,
The case was presented to highlight its rarity and pathogenesis.
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[Figure 1], [Figure 2]