From the Department of Ophthalmology (M. Haruta, CT, RY), Kurume University School of Medicine, Kurume; and the Department of Ophthalmology and Visual Sciences (M. Hangai), Kyoto University Graduate School of Medicine, Kyoto, Japan.
Supported by Grant-in-Aid for Scientific Research (KAKENHI) from Ministry of Education, Culture, Sports, Science and Technology, Japan.
Presented at Kyushu Ganka Gakkai; May 27–29, 2011; Okinawa, Japan.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Masatoshi Haruta, MD, PhD, Department of Ophthalmology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan. E-mail: firstname.lastname@example.org
Choroidal osteoma is a rare tumor composed of mature bone that usually affects young healthy women.1 It typically appears as a slightly elevated, orange-white, juxtapapillary choroidal tumor with well-defined margins.1 Some choroidal osteomas have been known to slowly grow in size and decalcify and then disappear over the years.1 Ultrasonography and computed tomography are of particular value in the clinical diagnosis of this tumor.2 Time-domain optical coherence tomography (TD-OCT) has been used to assess the status of the overlying retina, but it has a limited ability to image choroidal tissue.3 Spectral-domain OCT (SD-OCT) allows imaging with greater axial resolution of the retinal layers and more detailed images of the choroid compared to TD-OCT. We present SD-OCT findings in a patient with decalcifying choroidal osteoma accompanied by a choroidal neovascular membrane (CNVM) and serous retinal detachment.
A 13-year-old girl presented with blurred vision in her left eye. Her best-corrected visual acuity was 1.5 in the right eye and 0.4 in the left eye. A school vision screening test performed 1 year earlier was normal in both eyes. Anterior segment findings were unremarkable. Fundus examination showed a normal fundus appearance in the right eye and an orange-white, well-defined choroidal mass in the posterior pole of the left eye (Figs. 1A and 1B). A gray subfoveal membrane with surrounding subretinal fluid and hemorrhage was observed, which was suggestive of a CNVM (Fig. 1B). B-scan ultrasonography demonstrated a highly reflective choroidal mass with posterior acoustic shadowing (Fig. 1C). Computed tomography revealed a plaque of bone density at the level of the affected choroid (Fig. 1D). A diagnosis of choroidal osteoma in the left eye was made.
Figure 1. Color fundus photograph of the right (A) and left (B) eyes showed the presence of the choroidal osteoma with a subfoveal choroidal neovascular membrane in the left eye. Combined A- and B-scan ultrasonography of the left eye demonstrated a highly reflective choroidal mass with posterior acoustic shadowing (C). Computed tomography revealed a plaque of bone density at the level of the affected choroid in the left eye (D).
Clinically, decalcification of the choroidal osteoma was recognized as a yellow-white region within the tumor, whereas the calcified portion appeared more orange, as has been previously reported.3 On fluorescein angiography, the decalcified portion of the choroidal osteoma showed marked hyperfluorescence in the early phase (Fig. 2A), whereas the calcified portion showed slight hyperfluorescence in the late phase (Fig. 2C). A gray subfoveal membrane demonstrated a lacy pattern of hyperfluorescence in the early phase, which was consistent with a CNVM (Fig. 2A). On indocyanine green angiography, both the decalcified and calcified portions exhibited hypofluorescence throughout the angiography procedure (Figs. 2B and 2D). In addition, multiple small vascular networks on the tumor surface were observed within the calcified portion (Figs. 2B and 2C).
Figure 2. Fluorescein angiography of the left eye showed marked hyperfluorescence at the decalcified portion of the choroidal osteoma in the early phase (A) and slight hyperfluorescence at the calcified portion in the late phase (C). A gray subfoveal membrane demonstrated a lacy pattern of hyperfluorescence in the early phase, which was consistent with a choroidal neovascular membrane (A). Indocyanine green angiography of the left eye exhibited hypofluorescence at the choroidal tumor in both the early (B) and late (D) phases. Multiple small vascular networks on the tumor surface could be identified within the calcified portion (B and C).
The retinal features overlying the choroidal osteoma were different between the decalcified and calcified portions. The SD-OCT findings over the area of the decalcified portion included serous retinal detachment, photoreceptor outer segment (OS) disorganization (loss and/or shortening of the OS and highly reflective granular spots in the posterior border of the OS), retinal pigment epithelial (RPE) atrophy, Bruch’s membrane deformations (such as disruption and bowing), and a subfoveal CNVM (Figs. 3C and 3D). In contrast, the retinal structures over the area of the calcified portion appeared to be preserved. The inner retinal structures anterior to the external limiting membrane appeared to be nearly intact. SD-OCT also allowed us to observe an abnormal choroidal cavity beneath the atrophic RPE. The choroidal cavity of the decalcified portion showed apparent thickening and the loss of a choroidal vascular appearance; the reflectivity was uniform, particularly beneath the deformed Bruch’s membrane. The maximal choroidal thickness reached at least 677 μm in the affected left eye (Fig. 3D) and remained 285 μm in the fellow right eye (Figs. 3A and 3B). The choroid was not visible beneath the CNVM (Fig. 3D).
Figure 3. Fluorescein angiography images of the right (A) and left (C) eyes and spectral-domain optical coherence tomography images of the right (B) and left (D) eyes were obtained simultaneously using Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). Retinal pigment epithelial atrophy, serous retinal detachment, photoreceptor outer segment disorganization, and a deformed Bruch’s membrane were all confined to the areas over the decalcified portion (D). Loss of vascular appearance and thickening of the choroid were evident, especially at the decalcified portion, but the choroid was not visible beneath the choroidal neovascular membrane (D). CNVM = choroidal neovascular membrane; ELM = external limiting membrane; IS/OS = photoreceptor inner/outer segment junction.
The clinical and histopathologic features of choroidal osteoma were first described in 1978, but the pathogenesis remains controversial.2 Theories have included choristomatous, inflammatory, traumatic, hormonal, and hereditary etiologies.1 Despite its benign histopathologic nature, choroidal osteoma can cause profound visual acuity loss over many years. Visual acuity loss may occur with an associated CNVM, retinal detachment, RPE atrophy, or tumor decalcification.4,5 Within 10 years, 56% to 58% of patients with choroidal osteoma were reported to have decreased visual acuity to 20/200 or worse.4,5 The choroidal osteoma in our case was accompanied by a CNVM, serous retinal detachment, RPE atrophy, and tumor decalcification at the fovea, all of which may have contributed to substantial visual acuity loss.
Fluorescein and indocyanine green angiography showed the presence of multiple small vascular networks on the tumor surface in our case (Figs. 2B and 2C). It is a helpful sign in differentiating a choroidal osteoma from a metastatic tumor, which rarely shows evidence of such vessels.2 B-scan ultrasonography and computed tomography are especially useful for differentiating choroidal osteoma from other clinically similar lesions.2 The results of B-scan ultrasonography and computed tomography suggested the presence of calcium within the affected choroid, supporting our clinical diagnosis of choroidal osteoma.
TD-OCT can help elucidate retinal abnormalities by creating cross-sectional images of the retina, but it depicts only minor choroidal details. TD-OCT images of choroidal osteoma in 22 cases revealed unique retinal features indicating that photoreceptor atrophy was associated with tumor decalcification.3 SD-OCT offers significant advantages over the traditional TD-OCT. These advantages include faster scanning speed, higher axial resolution imaging, and more reproducible results. Using SD-OCT, we also confirmed a similar relationship between photoreceptor atrophy and tumor decalcification. RPE atrophy, serous retinal detachment, and photoreceptor OS disorganization were all confined to the areas over the decalcified portion. Decalcification is clinically defined as the yellow-white region within the tumor,3 and the yellow-white color is probably caused by the degeneration of the normally orange RPE overlying the white osseous tumor.2 Therefore, clinical tumor decalcification and RPE atrophy may be directly related. Degeneration of the RPE–Bruch’s membrane complex is thought to contribute to the development of the CNVM and subsequent retinal detachment.6 On SD-OCT, the CNVM was detected as a thick hyperreflective layer, with posterior shadows that interrupted the visualization of underlying structures.
A few histopathologic studies of the choroidal osteomas showed cross-sectional images of the affected choroids; however, those studies were based on eyes enucleated due to misdiagnoses of malignant melanomas, as occurred earlier.1,2 SD-OCT can provide a noninvasive cross-sectional image of the choroid up to 1,000 μm, which may be used to quantify choroidal thickness.7 We found that the choroid of the affected eye was much thicker than that of the normal fellow eye. In addition, SD-OCT examination showed a sudden increase in the choroidal thickness at the border of the calcified to decalcified portions (Figs. 3C and 3D). Therefore, choroidal thickening may be associated not only with the choroidal osteoma but also with tumor decalcification. The choroid of the decalcified portion appeared to have lost the highly reflective pattern that represents the choroidal vasculature, including the choriocapillaris, and acquired uniform reflectivity. Thus, the thickened choroid of the decalcified portion in our case likely had a destructive vascular structure, which was different from the thickened choroid with vascular structures reported in Vogt–Koyanagi–Harada disease and central serous chorioretinopathy.7,8
We recognize the limitations of a single case report and the rarity of this tumor. Nevertheless, we successfully revealed unique tomographic features specific to the decalcified portion of choroidal osteomas on SD-OCT, such as outer photoreceptor layer damages, RPE atrophy (a deformed Bruch’s membrane), and thick choroid without a vascular appearance. Some of these features were not evident when observed using TD-OCT. SD-OCT studies of a larger number of choroidal osteomas, from more subjects and more events, would provide important information on the pathogenesis and clinical course of this disorder.
- Shields CL, Shields JA, Augsburger JJ. Choroidal osteoma. Surv Ophthalmol. 1988;33:17–27. doi:10.1016/0039-6257(88)90069-0 [CrossRef]
- Gass JD, Guerry RK, Jack RL, Harris G. Choroidal Osteoma. Arch Ophthalmol. 1978;96:428–435. doi:10.1001/archopht.1978.03910050204002 [CrossRef]
- Shields CL, Perez B, Materin MA, Mehta S, Shields JA. Optical coherence tomography of choroidal osteoma in 22 cases: evidence for photoreceptor atrophy over the decalcified portion of the tumor. Ophthalmology. 2007;114:e53–e58. doi:10.1016/j.ophtha.2007.07.037 [CrossRef]
- Aylward GW, Chang TS, Pautler SE, Gass JD. A long-term follow-up of choroidal osteoma. Arch Ophthalmol. 1998;116:1337–1341.
- Shields CL, Sun H, Demirci H, Shields JA. Factors predictive of tumor growth, tumor decalcification, choroidal neovascularization, and visual outcome in 74 eyes with choroidal osteoma. Arch Ophthalmol. 2005;123:1658–1666. doi:10.1001/archopht.123.12.1658 [CrossRef]
- Grand MG, Burgess DB, Singerman LJ, Ramsey J. Choroidal osteoma: treatment of associated subretinal neovascular membranes. Retina. 1984;4:84–89. doi:10.1097/00006982-198400420-00002 [CrossRef]
- Maruko I, Iida T, Sugano Y, et al. Subfoveal choroidal thickness after treatment of Vogt-Koyanagi-Harada disease. Retina. 2011;31:510–517. doi:10.1097/IAE.0b013e3181eef053 [CrossRef]
- Maruko I, Iida T, Sugano Y, Ojima A, Ogasawara M, Spaide RF. Subfoveal choroidal thickness after treatment of central serous chorioretinopathy. Ophthalmology. 2010;117:1792–1799. doi:10.1016/j.ophtha.2010.01.023 [CrossRef]