The authors report a case of bilateral diffuse uveal melanocytic proliferation associated with transitional cell carcinoma of the bladder. A novel imaging finding on indocyanine green angiography of a “string of sausages” pattern in the large choroidal vessels is described. This occurs in areas of alternating retinal pigment epithelial hypertrophy and destruction, which is likely to be its cause. To the authors' knowledge, it has not been previously described.
[Ophthalmic Surg Lasers Imaging Retina. 2019;50:525–528.]
Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a rare paraneoplastic syndrome. Histologically, it is characterized by melanocyte proliferation in the iris and choroid, sparing the choriocapillaris, together with areas of retinal pigment epithelial (RPE) hypertrophy and degeneration.1 Patients with this condition develop bilateral rapid onset vision loss due to cataract, exudative retinal detachment, and retinal degeneration.1 We report a case of BDUMP with a previously undescribed imaging feature on indocyanine green angiography (ICGA).
A 74-year-old man presented with a 2-month history of darkening of the central vision of his left eye. There was no subjective change to the right eye, which had pre-existing poor vision. His past medical history was significant for a locally invasive transitional cell carcinoma of the bladder diagnosed 6 months prior to this presentation, which was managed with a combination of cysto-prostatectomy and adjuvant chemotherapy.
At the initial ophthalmological examination, the patient's best-corrected visual acuity (BCVA) was 6/76 in the right eye and 6/30 in the left eye. Posterior subcapsular cataracts were present. Fundus examination revealed round, pigmented subretinal lesions, irregular dark areas surrounded by an intensely orange fundus, and multifocal areas of subretinal fluid (Figure 1). The choroid was diffusely thickened on B-scan ultrasonography and the round, pigmented subretinal lesions seen on biomicroscopy were hyperechoic. Macular optical coherence tomography (OCT) findings were bilateral subretinal fluid (SRF), alternating areas of RPE destruction and thickening, and gross intraretinal cyst formation only in the right eye (Figure 2). Fundus autofluorescence (FAF) showed striking patches of hypoautofluorescence corresponding to irregular dark areas on biomicroscopy within an extensive area of hyperautofluorescence extending out from the optic discs corresponding to the orange areas on biomicroscopy (Figure 3). The round, pigmented subretinal lesions were not evident on FAF (Figure 3). The fluorescence pattern on fundus fluorescein angiography (FFA) was the inverse to that of FAF (Figure 4). There were also areas of pinpoint leak on FFA that increased in the late phase within areas of window defects (Figure 4). ICGA revealed blocked fluorescence in the location of the round, pigmented subretinal lesions and a “string of sausages” pattern of the large choroidal vessels in the areas of alternating fluorescence seen on FAF and FFA (Figure 5). The diagnosis of BDUMP was made based on the clinical findings, the results of the various imaging techniques, and the recent history of carcinoma.
Ultra-widefield imaging of the right eye (A) and the left eye (B).
Macular ocular coherence tomography of the right eye (A) and the left eye (B).
Fundus autofluorescence of the right eye (A) and the left eye (B).
Early and late-phase fluorescein angiography of the right eye (A, C) and the left eye (B, D).
Low- and high-magnification images of indocyanine angiography in the right eye (A, C) and the left eye (B, D).
The imaging features of our case are typical for BDUMP and can be linked to the histopathological changes found in these eyes.2–5 The round, pigmented subretinal lesions are due to focal accumulation melanocytes.2–5 The bilateral SRF is likely explained by leak from the choroid through the areas of pinpoint hyperfluorescence that increase in size in the late phase of the FFA (Figures 2 and 4). These are in areas of RPE destruction as demonstrated by window defects on FFA and hypoautofluorescence on FAF (Figures 3–5). The areas of RPE destruction are dark on biomicroscopy, likely due to diffuse melanocytic accumulation in the choroid (Figure 1). These are surrounded by a diffuse and intensely orange fundus appearance that correspond to areas of RPE proliferation and likely lipofuscin accumulation. The imaging features on OCT, FAF, and FFA are consistent with this (Figures 2–4). These areas also correspond to the ICGA sign of a “string of sausages” pattern in the large choroidal vessels and are likely its cause. To our knowledge, this has not been described previously. We propose that the RPE hypertrophy with lipofuscin accumulation block the fluorescence of the large choroidal vessels on ICGA. Its reticular pattern is responsible for the “string of sausages” appearance on ICGA. This novel ICGA feature described in this case report may also be useful in the diagnosis of this rare paraneoplastic condition.
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