High-resolution spectral-domain optical coherence tomography (SD-OCT) is a new exciting technology for visualization of microstructural alterations in retinal diseases.1 We investigated the applicability of this noninvasive method to detect in vivo early vitreous seeding of a histologically proven choroidal melanoma with transretinal tumor extension (Knapp-Rønne melanoma).
A 68-year-old man had blurred vision and inferotemporal visual field defect of the right eye for 4 months. His visual acuity was 20/30 OD and 20/20 OS. On funduscopy, a large pigmented choroidal mass with overlying hemorrhages was observed in the superonasal quadrant (Figure, A). Subretinal fluid around the tumor and inferior serous retinal detachment were present. Echography revealed a solid mass of 4.8-mm prominence, 11.2 × 10.6 mm2 base, and low homogeneous reflectivity, with a more reflective apical cap, implying a uveal melanoma rupturing the Bruch membrane and covered by an apical hemorrhage (Figure, B). Ultrasound could neither exclude nor confirm tumor extension through the retina.
The patient was investigated using a commercially available SD-OCT (Spectralis HRA+OCT; Heidelberg Engineering, Heidelberg, Germany). Discrete, irregularly spheroidal bodies were present in the vitreous (Figure, C). The retina overlying the tumor showed thinning toward the tumor apex where the retina was completely obliterated and particles 20 to 30 μm in size could be detected in the immediately adjacent vitreous, suggesting transretinal seeding of the uveal melanoma (Figure, D). Without evidence of a primary or metastatic lesion elsewhere in the body, the tumor was classified as T2a N0 M0, according to the 2009 tumor, node, metastasis (TNM) classification system.2 Enucleation of the right eye was performed.
Macroscopically, the sectioned globe disclosed a 5 mm-high, 12 mm-wide, gray-white mass with a prominent brownish cap and dark pigmented foci (melanin) on the tumor surface (Figure, E). Histopathological examination revealed a choroidal mixed-cell–type melanoma rupturing the Bruch membrane and showing intratumoral and supratumoral hemorrhages (Figure, F). Severe atrophic and degenerative changes were present in the overlying retina. At the tumor apex, the thinning had progressed to obliteration of the retina with absence of the internal limiting membrane. Within the supratumoral hemorrhage, melanoma cells could be found percolated through the attenuated retina and into the immediately adjacent vitreous (Figure, F, insert). Immunohistochemically, these intravitreal cells were positive for S-100, HMB-45, PNL2, melan-A, tyrosinase, and MITF, but negative for iron stain.
In our patient, the clinical suspicion of transretinal seeding by a uveal melanoma raised by SD-OCT could be confirmed histologically. Primary choroidal melanoma with retinal perforation and extension into the vitreous (Knapp-Rønne type) is a rare entity occurring in about 1 in 250 of uveal melanomas.3,4 Detection of retinal perforation is valuable owing to increased risk of recurrent vitreous hemorrhage after radiotherapy and increased likelihood of rhegmatogenous retinal detachment after transscleral local resection.
However, early recognition of Knapp-Rønne melanoma can sometimes be a clinical challenge because ophthalmoscopic assessment, and even echography with a resolution of approximately 100 μm, might sometimes be too imprecise for imaging of focal retinal perforation.
In contrast, conventional OCT produces cross-sectional images with approximately 10-μm resolution for visualization of microstructural alterations in retinal diseases1 as well as of the overlying retina in choroidal tumors.5,6 Recently, SD-OCT technology has improved resolution up to 3.5 μm per pixel.1
Using this technique, we could detect spheroidal bodies in the vitreous and, particularly, adjacent to the tumor apex where the overlying retina was completely obliterated. Although SD-OCT allows no exact differentiation between melanoma cells, melanomacrophages, or clusters of blood cells, our clinical findings presumed a Knapp-Rønne melanoma that could be confirmed histologically.
In the future, SD-OCT might become a helpful tool for clinical detection of vitreous seeding from uveal melanomas.
Correspondence: Dr Heindl, Department of Ophthalmology and University Eye Hospital, University Erlangen-Nürnberg, Schwabachanlage 6-91054 Erlangen, Germany (firstname.lastname@example.org).
Financial Disclosure: None reported.
Additional Contributions: We thank Carmen Hofmann-Rummelt, MTA, and Robert Lämmer, MD, for expert technical assistance and advice.
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