In vivo confocal microscopy of pre-Descemet corneal dystrophy associated with X-linked ichthyosis: a case report

Abstract

Background: Pre-Descemet corneal dystrophy (PDCD) is characterized by the presence of numerous, tiny, polymorphic opacities immediately anterior to Descemet membrane, which is a rare form of corneal stromal dystrophy and hard to be diagnosed. In vivo confocal microscopy (IVCM) is a useful tool to examine the minimal lesions of the cornea at the cellular level. In this article, we report a rare case of PDCD associated with X-linked ichthyosis and evaluate IVCM findings.

Case presentation: We present a 34-year-old male Chinese patient with PDCD associated with X-linked ichthyosis. Slit-lamp biomicroscopy showed the presence of tiny and pleomorphic opacities in the posterior stroma immediately anterior to Descemet membrane bilaterally. IVCM revealed regular distributed hyperreflective particles inside the enlarged and activated keratocytes in the posterior stroma. Hyperreflective particles were also observed dispersedly outside the keratocytes in the anterior stroma. Dermatological examination revealed that the skin over the patient's entire body was dry and coarse, with thickening and scaling of the skin in the extensor side of the extremities. PCR results demonstrated that all ten exons and part flanking sequences of STS gene failed to produce any amplicons in the patient.

Conclusions: IVCM is useful for analyzing the living corneal structural changes in rare corneal dystrophies. We first reported the IVCM characteristics of PDCD associated with X-linked ichthyosis, which was caused by a deletion of the steroid sulfatase (STS) gene, confirmed by gene analysis.

Keywords: In vivo confocal microscopy; Pre-Descemet corneal dystrophy; Steroid sulfatase; X-linked ichthyosis.

Fig. 1

Anterior segment photograph of the right eye. Slit-lamp biomicroscopy showing tiny, pleomorphic, greyish or brownish opacities in the posterior stroma anterior to Descemet membrane

Fig. 2

IVCM images of the cornea. a Normal appearance of superficial epithelium with prominent nuclei. b Normal appearance of parallel subbasal nerves. c Anterior stroma with normal-sized keratocytes and extracellular hyperreflective particles. d Mid stroma with normal cell density and keratocyte morphology. e Posterior stroma with enlarged hyperreflective keratocytes and regularly distributed hyperreflective particles. f Normal appearance of the endothelium

Fig. 3

Photograph of the left leg. It showed the thickened “fish scale” appearance of the skin

Fig. 4

PCR analysis of STS gene. There was a complete deletion in spanning Exon1-Exon10 (a) and flanking sequences DXS1139-DXS22S1 (b) in the patient,while his father and 2 unrelated healthy volunteers had no such deletion. Lanes 1–4 correspond to the patient, his father and 2 normal controls