Mosaic chromosome 18q partial deletion syndrome with bilateral full-thickness corneal disease: surgical intervention and histopathology

A 2-month-old boy diagnosed with a mosaic chromosome 18q partial deletion syndrome was referred for bilateral cloudy corneas. The abnormal metaphases had a terminal deletion of the long arm of chromosome 18 as clonal abnormality. The cytogenetics findings were 46,XY, del (18)(q21.2)[12]/46,XY[20]. Ocular findings included bilateral microcornea with dense opacification and unilateral iris and chorioretinal coloboma. Penetrating keratoplasty (PK) was performed on both eyes. Histopathology of the host corneal button showed complete loss of Bowman's layer, hyperkeratosis of the epithelium, stromal neovascularization, and leukocyte infiltration. Descemet's membrane and endothelium were irregular in both specimens. CD45 stain for leukocytes confirmed perivascular and epithelial leukocytes infiltration. Mosaic chromosome 18q deletion syndrome is a rare genetic abnormality with a variable phenotype - including ocular findings - and hence, warrants an ophthalmic evaluation and genetic counseling.