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Case report: unusual maculopathy presents a diagnostic challenge
The authors discuss differential diagnosis of an uncommon serous detachment with subretinal fibrin.
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A 29-year-old-healthy man presented to our retina service with a history of sudden, painless diminution of vision in the right eye lasting 2 days. He reported seeing a “black spot” in front of his right eye, which obscured the clarity of vision with associated metamorphopsia. The patient had a febrile illness 7 days before the onset of ocular symptoms, diagnosed as an upper respiratory tract infection, for which he received treatment by an internist. There was no history of tinnitus or any dermatological lesion.
His history was significant for an episode of blurred vision in both eyes 2 months before, which subsided within 1 week. He did not visit an ophthalmologist at that time.
There was no past history of Koch’s. The patient gave no history of the use of steroids in any form. He reported no history of diabetes or hypertension.
Examination
On ophthalmic examination, his best corrected visual acuity was 1/60 in the right eye and 6/6 in the left eye. Slit-lamp examination in both eyes was within normal limits and there was no relative afferent pupillary defect. IOP by applanation tonometry was 12 mm Hg in both eyes. Dilated fundus examination revealed normal discs and retinal vasculature in both eyes.
The right eye revealed 1+ vitreous cells in the posterior vitreous cavity. The same eye had a large, well-defined area of serous detachment at the posterior pole with a pale yellow ellipsoidal “halo” lesion at the macula and an area of subretinal yellow deposition measuring one disc diameter at the lower part of the larger lesion. There were fine retinal striae radiating out of the halo, limited to the area of serous detachment (Figure 1).
In the left eye there was a well-defined pocket of subretinal fluid inferonasal to the disc, with retinal pigment epithelium alterations in the superotemporal quadrant and inferonasal to the macula (Figure 2).
The macular vasculature could be seen clearly over the lesion. The retinal periphery was normal on scleral depression.
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Discussion
The causes of serous detachment at the posterior pole include idiopathic central serous chorioretinopathy (ICSC), choroidal neovascular membrane (CNVM), retinal pigment epithelial detachment (RPED), adult foveomacula vitelliform dystrophy (adult Best’s macular dystrophy), subretinal cysticercosis, Vogt-Koyanagi-Harada (VKH) syndrome, idiopathic polypoidal choroidovasculopathy (IPCV), hypertensive retinopathy, diabetic nephropathy-related maculopathy and optic nerve head pit with associated serous detachment.
Other uncommon causes include idiopathic serpiginous choroiditis, acute posterior multifocal placoid pigment epitheliopathy (APMPPE), uveal effusion syndrome, choroidal tumor-related serous detachments and lymphoid hyperplasia of the choroids.
The peculiar clinical picture and angiographic features was atypical of any of these entities, making our case unique.
ICSC is characterized by serous detachment of the retina, usually involving the macula, occurring in young healthy men. Although in most cases the diagnosis is made clinically, fundus fluorescein angiography is helpful in providing a definitive diagnosis characterized by the presence of an expanding leak or smokestack appearance, which was not seen in this case.
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CNVM is a common cause of detachment of the posterior pole and is characterized clinically by the presence of subretinal neovascular membrane associated with subretinal hemorrhage or exudative fluid, which is clearly demarcated on angiogram. In occult CNVM the membrane is usually not well seen either clinically or angiographically. CNVMs are usually seen in age-related macular degeneration occurring in people more than 50 years of age. CNVMs, although rare, can occur in this age group and are called idiopathic CNVM. There was no evidence of CNVM in our case, clinically or angiographically.
RPED can occur in an isolated form or in association with CNVM or ICSC. Fluorescein angiogram usually shows a slow-filling, well-defined, blister-like cavity. Large RPEDs, especially of the size as seen in our patient, are rare.
Adult vitelliform macular dystrophy is a rare autosomal-dominant disorder with characteristic stages in the evolution of the disease process. Stage 3 (pseudohypopyon stage) is typified by the occurrence of bilateral symmetrical round yellow sub-foveal deposits at the macula. Although a normal electro-oculogram (EOG) can be seen in adult vitelliform macular dystrophy (as seen in our case), the angiographic picture was not typical of this disorder.
Subretinal cysticercosis is a rare entity wherein a cystic lesion can be seen under the detached retina. It is usually associated with ocular inflammation, vitritis and retinal edema. Ultrasound B-scan is diagnostic, showing a classical subretinal hypoechoic cavity with a hyperechoic lesion of the scolex. The absence of this diagnostic picture on ultrasound B-scan and a clear vitreous cavity rule out this possibility.
The absence of vitritis and choroidal thickening on ultrasound B-scan ruled out VKH. The angiographic features were also not suggestive of VKH.
IPCV, or posterior uveal bleeding syndrome, is characterized by regularly round serous and hemorrhagic detachments of the retinal pigment epithelium, detachments apparently derived from large vascular channels. The lesions cluster around the optic nerve and drusen, and macular RPE changes are conspicuously absent. Digital pressure on the globe will not collapse these lesions. The absence of placoid areas of hyperfluorescence on fluorescein angiogram typical of IPCV ruled out this rare entity.
There was no evidence of an optic nerve head pit. Systemic examination failed to reveal the presence of diabetes or hypertension.
Fundus fluorescein angiogram revealed normal filling of retinal vasculature. There was an area of hyperfluorescence inferior to the macula in the right eye, which increased in size and intensity in the late phases with leakage in the surrounding areas (Figure 3). There was an area of blocked hypofluorescence above this area, with a rim of hyperfluorescence suggestive of slow filling of a cavity, with a well-demarcated “fluid” level between the hyper- and the hypofluorescent zones (Figure 4).
In the left eye there was a large area of “mottled” hyperfluorescence inferonasal to the macula with a fluid-filled hyperfluorescent cavity infero- nasal to the disc (Figure 5), and multiple areas of well-circumscribed discrete hyperfluorescent lesions in the superior and nasal peripapillary region (Figure 6).
Ultrasound B-scan was done to rule out the presence of subretinal cysticercosis and evidence of choroidal thickening. There was an area of retinal elevation at the macula in the right eye and the peripapillary region in the left, with no evidence of a subretinal cyst (Figure 7). There was no evidence of choroidal thickening. EOG was within normal limits.
Based on the fundus examination and typical fundus fluorescein angiographic features, a diagnosis of acute idiopathic maculopathy (AIM) was made.
The patient was kept on regular follow-up and no treatment was administered. When last seen, 1 month after the initial presentation, the fluid at the posterior pole had decreased in the right eye both clinically and angiographically (Figures 8, 9). The lesion in the left eye showed evidence of residual fluid (Figure 10), leaving RPE alterations that appeared as “window defects” on angiogram (Figure 11). Vision in the right eye had improved to 3/60.
The patient was advised to maintain regular follow-up.
Discussion
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AIM is a rare disorder originally described by Yannuzzi et al in 1991. Since then, a little more than 30 cases of this syndrome have been reported in the literature. Each of the nine patients in the initial series had an acute onset of exudative maculopathy in one eye and shared certain clinical and epidemiological features. With recent reports of several bilateral cases, the entity hitherto known as unilateral acute idiopathic maculopathy (UAIM) has been renamed as AIM.
The typical clinical features of AIM are sudden onset of severe visual loss with a complaint of central metamorphopsia or central scotoma. The visual symptoms typically appear after the onset of a flu-like illness. Clinical findings reported in the literature include irregular neurosensory retinal detachment overlying a smaller grayish thickening at the level of the RPE.
The subretinal exudate can be fibrinous resembling that of ICSC, pale-yellow and thick resembling Best’s disease or fluffy-white, suggestive of inflammatory cells or debris. In a few cases intraretinal hemorrhages and inflammatory cells in the posterior vitreous have been reported. Anterior segments are always quiet. Papillitis and subtle prominence and tortuosity of retinal vasculature have also been described. While all the initial cases described were unilateral, three subsequent cases with bilateral involvement were reported, prompting a change in nomenclature.
The fundus fluorescein findings of AIM demonstrate early hyperfluorescence at the level of the RPE lesion and complete staining of the overlying neurosensory retinal detachment. The pattern of late hyperfluorescence is similar to the homogenous leakage seen beneath a serous pigment epithelial detachment. There are no pathognomic angiographic features of this rare syndrome, so the diagnosis is one of exclusion.
Although the cause of AIM is still obscure, an inflammatory process, predominantly involving the RPE and to a lesser degree affecting the optic nerve, is suspected. The frequent history of a preceding flu-like illness and the presence of papillitis and vitreous cells are suggestive of an inflammatory pathology. Despite extensive diagnostic studies for infections and inflammatory disorders, none of the patients had any positive findings.
The natural course of AIM is rapid, with complete resolution of exudative changes, near-complete resolution of the exudative changes with evidence of RPE atrophy or hyperplasia and near-complete restoration of visual acuity as seen in our case. No specific treatment is prescribed, although a few cases have been treated with oral steroids. Since AIM is a rare clinical entity, one needs to maintain a high index of clinical suspicion when confronted with a patient presenting with bilateral exudative maculopathy.
To reach a diagnosis of AIM, we devised the following flowchart. ICSC and CNVM are the first entities to be ruled out. ICSC with underlying large RPE detachments and occult CNVMs can mimic AIM clinically, but can be differentiated angiographically, especially by indocyanine green. Adult Best’s macular dystrophy, although a rare entity, is ruled out based on the usual symmetrical nature of the disease (adult Best’s disease also has normal EOG, so it cannot be a differentiating feature). Isolated large RPE detachments are rare in this age group and still rarer as a bilateral entity, and can be differentiated based on the absence of inflammation (vitreous cells, papillitis).
Finally, APMPPE, which shares several clinical and demographic features with AIM, can be differentiated by the absence of neurosensory detachments and intraretinal hemorrhages, never seen in APMPPE. Bilaterality in AIM has led many to speculate that these two entities may actually be different manifestations of a related underlying pathophysiologic process.
In conclusion, AIM is a distinct entity with unique clinical and angiographic features. One needs to maintain a high index of clinical suspicion to differentiate it from other inflammatory entities, which may pose a diagnostic dilemma.
For Your Information:
- Surbhit Choudhry, MD, and Aarti S. Choudhry, MD, can be reached at ICARE Eye Hospital and Postgraduate Institute, E-3a, Sector 26, Noida, UP, India; (91) 255-5969 or 255-8274; fax: (91) 0120-255-6389; e-mail: icare@vsnl.com; Web site: www.icarehospital.org.
References:
- Yannuzzi LA, Jampol LM, et al. Unilateral acute idiopathic maculopathy. Arch Ophthalmol. 1991;109:1411-1416.
- Freund KB, Yannuzzi LA, et al. The expanding clinical spectrum of unilateral acute idiopathic maculopathy. Arch Ophthalmol. 1996;114:555-559.
- Hanutsha P, Yannuzzi LA, Freund KB. The occurrence of uncommon intraocular inflammatory diseases: A survey of the Macula Society. Retina. 1996;16:437-439.
- Fish RH, Territo C, Anand R. Pseudohypopyon in unilateral acute idiopathic maculopathy. Retina. 1993;13:26-28.
- Yannuzzi LA, Slakter JS, et al. Digital indocyanine green videoangiography and choroidal neovascularization. Retina. 1992;12:191-223.
- Guyer DR, Yannuzzi LA, et al. Digital indocyanine green videoangiography of central serous chorioretinopathy. Arch Ophthalmol. 1994;112:1057-1062.