Abstract
Purpose: :
To investigate the cause of incorrect pathologic diagnosis after penetrating keratoplasty for corneal opacification associated with Schnyder’s corneal dystrophy (SCD).
Methods: :
Retrospective chart review of 124 patients under IRB approval with SCD from 1989 to 2009. All patients had a diagnosis of SCD by ophthalmologist or JSW. Photographs and slit lamp findings of patients not personally examined by JSW were reviewed to confirm diagnosis. Charts and genetic testing of those patients who had non-definitive clinical or pathologic diagnosis indicating entity other than SCD, were identified.
Results: :
5 eyes of 4 patients, all male, met criteria. Mean age at penetrating keratoplasty (PKP) was 65.75 years, ranging 52 to 80 years. On chart review, all six eyes had documented classic corneal changes including peripheral arcus and central haze. No eyes had corneal crystals. Genetic testing after PKP confirmed mutations in the UBAID1 gene, causative of SCD in all 4 patients. Lipid stains of the corneal specimen were not performed in any of the misdiagnosed cases. They could not be performed subsequently because lipid was dissolved out and tissue could not be specially processed.Patients one had a diagnosis of Central Cloudy Dystrophy of Francois (CCDF) prior to PKP. Pathology report indicated ‘endothelial corneal degeneration with bullous keratopathy’. Sibling to patient one, patient two had no diagnosis and was indicated to have CCDF on post-operatively. Patient three had a diagnosis of "atypical granular dystrophy", subsequently changed to SCD prior to PKP. No preoperative information was submitted to the pathologist whose report read ‘Fuch’s endothelial dystrophy with focal loss endothelial cells’. Patient four initially had a pathologic diagnosis of ‘lattice and band keratopathy’ from positive amyloid staining. After first PKP, clinical photos were reviewed and SCD considered. PKP of second eye was stained with oil red O confirming lipid deposition characteristic of SCD.
Conclusions: :
Since corneal crystals are only present in 50% of patients with SCD, diagnosis without crystals is challenging. Our study demonstrates, that if the pathologist does not receive information that SCD is suspected; the tissue may not be processed appropriately and the opportunity to perform lipid stains may be lost. Due to the variable presentation of SCD, genetic testing should be considered in the final diagnostic evaluation.
Keywords: cornea: clinical science • pathology: human • crystallins