Macular corneal dystrophy

Macular corneal dystrophy (MCD), an autosomal recessive corneal stromal dystrophy, is caused by mutations in the carbohydrate sulfotransferase 6 gene (CHST6), located at 16q22. This dystrophy is characterized by diffuse stromal haze that extends from limbus to limbus and is associated with poorly demarcated focal opacities (macules) (Fig 6-23A). Histologically, H&E staining shows subtle eosinophilic stromal deposits. Alcian blue and colloidal iron stains highlight nonsulfated glycosaminoglycan deposits, which accumulate intracellularly in the stromal keratocytes and endothelium and extracellularly in the stroma (Fig 6-23B, C). Pathologic changes in the endothelium are frequently accompanied by guttae in the Descemet membrane (Fig 6-23D). See Table 6-1 for a histologic comparison of LCD1, GCD1, GCD2, and MCD.

Figure 6-21 Granular corneal dystrophy type 1. A, Clinical photograph. Note the well-demarcated stromal opacities with clear intervening stroma. B, H&E stain. Note the eosinophilic deposits (arrows) at all levels of the corneal stroma. C, Masson trichrome stain. The stromal collagen stains blue, and the granular hyaline deposits stain brilliant red.

• Aggarwal S, Peck T, Golen J, Karcioglu ZA. Macular corneal dystrophy. Surv Ophthalmol. 2018; 63(5):609–717.

Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.