Choroidal osteoma is an acquired, benign tumor of the choroid which usually forms near the optic disc or macula. Histologically, it consists of irregular spicules of mature cancellous bone within a vascular connective tissue stroma. It is diagnosed most often in young women, and produces variable symptoms relating to its size and location. Most choroidal osteomas do not require active intervention. Choroidal neovascularization occasionally develops at the margins of long-standing lesions, and is treated with laser photocoagulation to minimize complications, including fluid leakage, bleeding and fibrosis.
A common presentation of lesions in the vicinity of the macula is variable loss of central vision with distorted shapes (metamorphopsia, caused by disruption of the spatial relationship between photoreceptors). When central vision is spared, patients occasionally notice visual field defects corresponding to the location of the tumor. Sudden loss of central vision may occur when choroidal neovascularization results in serous or hemorrhagic retinal detachment involving the macula.
Choroidal osteomas first appear as orange, slightly elevated lesions with very well-defined, scalloped or geographic margins. They are usually located adjacent to the optic disc or at the macula. Over subsequent years, with progressive atrophy of the retinal pigment epithelium (RPE), they develop a pale-yellow hue with mottled surface pigmentation.
Characteristic, small vascular networks may also be visible on the surface. Visual field defects corresponding to the tumor location are present. Choroidal neovascular membranes occasionally develop at the edges of established lesions. These collections of abnormal, leaking vessels result in the accumulation of subretinal lipid-rich exudates and predispose to visionthreatening complications such as serous macular detachment and subretinal or vitreous hemorrhage.
Rare. Up to 20 percent of cases are bilateral.
Regular review is required to detect choroidal neovascularization or a previously undiagnosed malignancy.
Choroidal melanoma; choroidal nevus; choroidal hemangioma; posterior scleritis; choroidal metastasis; Best disease (vitelliform macular dystrophy).
Choroidal neovascularization; Age-related macular degeneration.
Ocular tests and imaging investigations
- B-scan ultrasonography demonstrates an echogenic, slightly elevated mass.
- Computed tomography (CT) of the orbit reveals a high-density lesion, resulting from the dense calcification within the tumor.
- Fluorescein angiography demonstrates irregular hyperfluorescence corresponding to RPE atrophy overlying choroidal osteomas. Neovascular vessels appear either as areas of hyperfluorescence that leak or in the late phase.
Review and treatment The prognosis of choroidal osteoma is unpredictable: some
Choroidal osteoma with neovascular membrane and associated hemorrhages.
lesions regress spontaneously, whereas others continue to enlarge. Annual review with fundus photography and/or fluorescein angiography is recommended to detect neovascularization, or changes in size or appearance (which may be suggestive of a previously undiagnosed malignant lesion).
Laser Choroidal neovascularization is treated with laser photocoagulation; several sessions may be required. Neovascularization at the macula is occasionally treated with photodynamic therapy (see Age-related macular degeneration).