Clinical Detection of Melanoma-Associated Spongiform Scleropathy by Ultrasound Biomicroscopy and Its Correlation With Pathological Diagnosis

Ciliary body and choroidal melanoma account for greater than 90% of all uveal melanomas. Extrascleral extension is an important prognostic factor in uveal melanoma and has been described in 8% of eyes enucleated in the Collaborative Ocular Melanoma Study. Infiltrating solid tumors may cause cellular and degenerative changes in connective tissue surrounding the tumor, contributing to tumor cell invasion.¹ For these reasons, characterization of scleral changes adjacent to the tumor may be relevant to tumor invasion.

Melanoma-associated spongiform scleropathy (MASS) is a histopathological entity described as an area within the sclera adjacent to a choroidal or ciliary body melanoma where collagen fibers appear to have disintegrated into loose fibers.² Melanoma-associated spongiform scleropathy is observed in approximately one-third of eyes with uveal melanoma.^2,3 Biochemical analyses of MASS show decreased collagen and amino acids and increased glycosaminoglycans and water uptake. This degradation process, mediated by matrix metalloproteinases,³ may weaken the structural barrier and facilitate local tumor invasion. Alyahya⁴ observed MASS in 91% of eyes with tumor invasion, in contrast to 23% of eyes without. We report for the first time the clinical detection of MASS by ultrasound biomicroscopy (UBM) in ciliary body melanoma, with histopathological correlation.

A 44-year old man presented with painless decreased vision in the right eye for several months. Visual acuity was 20/25, and on dilated examination a melanocytic ciliochoroidal mass was identified abutting the lens (Figure 1A). Gonioscopy showed a pigmented mass invading the anterior chamber angle (Figure 1B).

B-scan ultrasound showed a large dome-shaped mass involving the ciliary body that measured 5.4 mm in thickness. There were cystic spaces in the lesion. A-scan demonstrated medium reflectivity with a decrescendo pattern. Ultrasound biomicroscopy showed intralesional cavities. The inner one-fourth of the sclera adjacent to the base of the tumor was hypoechoic compared with the outer three-fourths of the sclera (Figure 2A). The thickness of the sclera over the lesion was deemed to be normal.

Diagnosis of a medium-sized, malignant, ciliochoroidal melanoma was made, and enucleation was performed.

Gross examination showed a pigmented superotemporal ciliary body mass measuring 6 × 9 × 4 mm. The ciliary body melanoma was composed of spindle B and epithelioid melanoma cells, with large cavities containing eosinophilic exudate. Tumor cells were noted in the anterior chamber angle and iris root (Figure 2B) and extended to the inner sclera only. The inner sclera adjacent to the tumor showed a pale staining area relative to the outer sclera and neighboring scleral regions (hematoxylin-eosin staining [H-E], Figure 2B). High-power examination showed a feathery appearance of the inner sclera and dot morphology of collagen fibers in contrast to the normal interlacing collagen fiber bundles in the surrounding sclera (H-E, Figure 2C). The diagnosis was ciliary body melanoma with MASS.

Ultrasound biomicroscopy has been a valuable tool in the detection and management of anterior segment and ciliary body tumors.⁵ Careful assessment of UBM characteristics of the tumor-scleral interface enables the detection of intrascleral invasion and small extrascleral tumor extension.⁶ Owing to the irregular arrangement of its collagen fibrils, the sclera produces ultrasound backscatter that results in uniform high reflectivity. The region of lower reflectivity involving the inner scleral layers adjacent to the tumor corresponded to MASS seen histopathologically. The observed low reflectivity likely relates to loose arrangement of collagen fibrils and increased water content. As MASS is a noninflammatory degradation process of scleral collagen that may facilitate tumor invasion, this observation may lead to larger studies to assess whether the clinical detection of MASS by UBM might have clinical or prognostic significance.

Correspondence: Dr Yücel, Ophthalmic Pathology Laboratory, University of Toronto, St Michael's Hospital, 30 Bond St, Shuter Wing 5-038, Toronto, ON M5B 1W8, Canada (yeni.yucel@utoronto.ca).

Financial Disclosure: None reported.