Hereditary crystalline stromal dystrophy of Schnyder. II. Histopathology and ultrastructure.

Although first described almost half a century ago (van Went and Wibaut, 1924) and firmly established as a distinct entity by Schnyder (I 929), proof that the crystalline deposits in this disorder are cholesterol was not forthcoming until quite recently (Delleman and Winkelman, I 968).Nearly 40 years ago Bonnet, Paufique, and Bonamour (I 934) demonstrated the presence of crystals which were birefringent and soluble in ether, and Sedan and Valles (I946) carried out specific histochemical staining for cholesterol, but in neither of these reports was the hereditary nature of the lesion established.Reports of bona fide cases of hereditary crystalline dystrophy examined histologically are scarce (Malbran, Paunessa, and Vidal, 1953; Paufique, Ravault, Bonnet, and Laurent, I964; Delleman and Winkelman, I968) and, apart from the case described by Offret, Payrau, Pouliquen, Faure, and Bisson (i 966), which must be accepted with some reservation since cholesterol crystals were not demonstrated, there is no account of the ultrastructural appearances in this condition.In this report we present the combined light and electron microscopical findings in an attested case, the clinical, genetic, and biochemical aspects of which have been described in the preceding paper (Bron, Williams, and Carruthers, 1972). Material and methodsA partial-thickness disc of cornea was removed from the left eye of a 47-year-old man with bilateral crystalline dystrophy of the Schnyder type (see Bron and others, I972 for clinical details).The specimen received in buffered glutaraldehyde was divided into three portions, one for paraffin- embedded section, one for frozen section, and one for electron microscopy.In addition to conventional staining with haematoxylin and eosin, sections were also examined for protein by the coupled tetrazonium method, for glycogen by the periodic acid-Schiff, Grocott- Gomori, and Best's carmine staining reactions (using diastase digested controls), and for acid polysaccharide by the Alcian blue method.Staining for fat was performed on frozen sections by the oil red 0 and Sudan black B techniques and specifically for cholesterol by the Schultz and Okamoto methods.The techniques employed were in most instances as described by Pearse (i 968).The specimen for electron microscopy was postfixed in Zetterquist's osmium tetroxide and em- bedded in araldite.Thick sections were cut and stained with toluidine blue for the purpose of orientation by light microscopy, after which sections for electron microscopy were cut on an LKB III ultratome at 500 to 8oo A, stained with uranyl acetate and lead citrate, and examined with an AEI-EM6 microscope.