An immunohistochemical study of the 'snowbank' in a case of pars planiti.
OBJECTIVE
To characterize the extracellular matrix and cellular components of a 'snowbank' removed during vitreous surgery for treatment of retinal detachment complicating pars planitis.


METHODS
The 'snowbank' was examined using immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies directed against glial fibrillary acidic protein (GFAP), cytokeratin, alpha smooth muscle actin, tenascin, laminin, fibronectin, and collagen types I, II, and III.


RESULTS
The 'snowbank' was acellular except on the uveal side where there were cytokeratin-positive retinal pigment epithelial cells. There were no cells positive for the glial cell marker GFAP and the myofibroblast cell marker alpha smooth muscle actin. The extracellular matrix of the 'snowbank' contained tenascin and collagen types I, II, and III. There was no immunoreactivity for laminin and fibronectin.


CONCLUSIONS
These results on the immunohistochemical components of the 'snowbank' may be useful in clarifying the nature of the chronic inflammatory process in pars planitis. They indicate extensive tissue repair and remodeling, leading to major loss of function.
Abu El-Asrar
Ahmed M
AM
Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia. abuasrar@KSU.edu.sa
Geboes
Karel
K
D000199:Actins / Q000378:metabolism; D000911:Antibodies, Monoclonal; D002648:Child; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism* / Q000473:pathology; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D007633:Keratins / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D007908:Lens, Crystalline / Q000601:surgery; D015868:Pars Planitis / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D012163:Retinal Detachment / Q000209:etiology / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D012591:Scleral Buckling; D019063:Tenascin / Q000378:metabolism; D014821:Vitrectomy
D000199:Actins; D000911:Antibodies, Monoclonal; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D005904:Glial Fibrillary Acidic Protein; D007797:Laminin; D019063:Tenascin; D007633:Keratins; D003094:Collagen