Editor/Author: Adrian Fung
A 41-year-old Caucasian female was referred by her optometrist with an unusual fundus lesion on routine eye examination.
She had not experienced any change in her vision and there was no significant past ocular history. Over the last 6 weeks she had experienced two episodes of intermittent “vertigo”. Past medical history included hypertension, polycystic ovarian syndrome, inflammatory bowel disease and depression. Past surgery history included cholecystectomy and appendectomy. There was no family history of any eye disease. She owned one cat. Medications included lercanidipine (Zircol) for hypertension and sertraline (Zoloft) for depression. On examination the visual acuities were 6/6 in the right eye (OD) and 6/4.5 in the left eye (OS). Intraocular pressures were 16mmHg OD and 17mmHg OS. There was no ocular melanocytosis, iris heterochromia or cervical lymphadenopathy. Anterior segment examination was normal with clear media in both eyes. The irides were brown. Fundus examination revealed a 0.7mm diameter slightly elevated yellow-white subretinal lesion 0.2mm temporal to the left optic disc (Figure 1). This lesion had an orange halo but no associated subretinal fluid. Drusen were present within the posterior poles of both eyes. Cup:disc ratios were 0.4 OD and 0.5 OS and the retinal periphery was normal.
What is your diagnosis?
The differential diagnosis of a non-pigmented isolated choroidal lesion includes: amelanotic choroidal nevus, amelanotic choroidal melanoma, choroidal metastasis, choroidal granuloma, choroidal osteoma and solitary idiopathic choroiditis.
Red free fundus photography highlighted the lesion (Figure 2), which was very slightly hyperautofluorescent (Figure 3). Optical coherence tomography (OCT) of the macula was normal, but a raster scan through the lesion demonstrated a scleral lesion with thinning of the overlying choroid. There was no associated subretinal fluid, and the overlying retina was normal (Figure 4). B-scan ultrasonography failed to clearly delineate any elevation. Blood tests were performed to exclude an inflammatory cause (Bartonella henselae for cat-scratch disease, syphilis serology) or granuloma (angiotensin converting enzyme for sarcoidosis). A tuberculosis skin test was performed and a chest X-ray ordered.
The signs and imaging results are consistent with solitary idiopathic choroiditis. The vertigo is thought to be unrelated.
The patient was asked to follow-up in 6 months to detect any progression in lesion size. All test results came back negative, except for syphilis serology which demonstrated a non-reactive RPR but positive treponemal antibody (CMIA) and TPHA. A referral was made to an infectious disease specialist for further investigation and management. A brain computed tomography (CT)-scan performed by the general practitioner for investigation of the vertigo was normal.
Solitary idiopathic choroiditis (SIC) is a rare condition first described in 1997 by Hong and associates.1 They identified 6 patients with solitary, yellow-white choroidal lesions of 1 disc diameter in diameter. They called the lesion “unifocal helioid (sun-like) choroiditis”. In 2002, Shields and associates2 studied a larger cohort of 60 patients and renamed the condition “solitary idiopathic choroiditis”. The lesion is most commonly found in Caucasians (93%) and is more common in females (63%). It is usually about 1 disc diameter in size, yellow (97%) and posterior to the equator (93%). No underlying cause was found in any of these patients. Recently, Fung and associates3 described multi-modal imaging characteristics of SIC. They described the lesions as being solid on ultrasound, hyperautofluorescent and arising as a scleral elevation on OCT. On OCT the overlying choroid was thinned. Although definitive localisation of SIC cannot be made without histopathology, these features are suggestive of a scleral lesion (such as a nodular scleritis) rather than choroiditis. Melanoma and metastasis should be excluded in any non-pigmented choroidal lesion. Choroidal melanoma has a variable autofluorescence, with just over 50% demonstrating hyperautofluorescence, usually in a heterogenous pattern.4 The lesion arises in the choroid, and is often associated with subretinal fluid and lipofuscin deposits. Most choroidal melanomas are echolucent. Choroidal metastases are often multiple and bilateral. Presence of a known malignancy should raise suspicion of a metastasis. Metastases have granular hyper- and hypoautofluorescent dots, with an autofluorescence pattern inverse to fluorescence seen on fluorescein angiography. 5 On OCT the reflectivity is low, the choriocapillaris is intact and the inner sclera is often visible.6 Syphilis needs to be excluded in most patients with inflammatory eye disease. RPR is a non-treponemal test that can be used to monitor disease activity and response to treatment. Treponemal antibody (CMIA) and TPHA are treponemal tests that are more sensitive and specific after initial infection, but do not discriminate between past and current infection. Presence of a negative RPR but positive TPPA may occur in primary syphilis, previously treated syphilis or latent syphilis. In these cases it is important to repeat the serology and refer to an infectious disease specialist. There is no known association between SIC and syphilis infection.
Take home points
1. Hong PH, Jampol LM, Dodwell DG, Hrisomalos NF, Lyon AT. Unifocal helioid choroiditis. Arch Ophthalmol 1997;115:1007-13. 2. Shields JA, Shields CL, Demirci H,. Honavar S. Solitary idiopathic choroiditis: the Richard B. Weaver lecture. Arch Ophthalmol 2002;120:311-9. 3. Fung AT, Kalicki S, Shields CL, Mashayekhi A, Shields JA. Solitary idiopathic choroiditis. Findings on enhanced depth imaging optical coherence tomography in 10 cases (In Press). 4. Shields CL, Bianciotto C, Pirondini C et al. Autofluorescence of choroidal melanoma in 51 cases. Br J Ophthalmol 2008;92:617-22. 5. Ishida T, Ohno-Matsui K, Kaneko Y, et al. Autofluorescence of metastatic choroidal tumor. Int Ophthalmol 2009;29:309-13. 6. Torres VLL, Brugnoni N, Kaiser PK, Singh AD. Optical coherence tomography enhanced depth imaging of choroidal tumors. Am J Ophthalmol 2011;151:586-93.e2.
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