Characterization of melanoma associated spongiform scleropathy

Melanoma associated spongiform scleropathy (MASS) describes areas within the sclera where collagen bundles appear to have disintegrated into loose fibres. It is found adjacent to choroidal and ciliary body melanoma. This study aimed to characterize these changes histopathologically.

Sections of 218 eyes that had been enucleated for malignant melanoma between January 1994 and June 2000 were examined for MASS, using data collected from the files of the Eye Pathology Institute, University of Copenhagen. Findings were correlated to patient characteristics (age, gender and pre-enucleation radiation) and tumour characteristics (location, morphology and invasion). Staining was applied using haematoxylin-eosin (HE), periodic acid-Schiff (PAS), haematoxylin-phloxine-saffron (HPS), alcian blue, colloidal iron and Masson's trichrome. Sixteen normal eyes and 29 eyes with diseases other than choroidal and ciliary body melanoma served as controls.

Melanoma associated spongiform scleropathy was observed in 73 of the 218 eyes (33%) with melanoma. No changes were found in normal eyes or in eyes with other intraocular diseases. A significantly higher incidence of MASS was found in older age groups. Thirty-six (49%) of the 73 cases of MASS were observed within a patient age range of 71-90 years, whereas only 14 cases (19%) were observed within an age range of 41-60 years. Pre-enucleation radiation significantly reduced the incidence of MASS. Twenty-two (10%) of the total 218 eyes had received pre-enucleation radiation and in only two (1%) of these was MASS observed. Melanoma associated spongiform scleropathy was found only in areas of contact between the tumour and the sclera, and the degree of MASS correlated directly with the extent of this contact. No significant correlation with tumour cell type was found.

In eyes with MASS, the severity of the changes correlated to the extent of direct contact between the tumour and sclera. Melanoma associated spongiform scleropathy showed a significant predilection towards older age groups. Pre-enucleation radiation significantly reduced the incidence of MASS. Melanoma associated spongiform scleropathy is probably caused by a deposition of amorphous material splitting the scleral collagen fibrils. This material may be secreted either directly from the adjacent tumour or from scleral fibroblasts stimulated by the tumour cells.