Background: A brown cornea is relatively rare. We report a case of progressive brown corneal pigmentation in a patient with a primary acquired melanosis of the conjunctiva. Later the patient developed an iris melanoma.
Methods: Case report with clinico-pathological correlation and discussion of possible mechanisms of particle clearance of the cornea.
Results: A 36-year-old female developed a corneal stromal pigmentation adjacent to a pigmented conjunctival lesion of the left eye. The corneal pigmentation had progressed through 8 years. The conjunctival lesion was surgically removed, and proved histopathologically to be a compound nevus with slight atypia and an acquired melanosis. Despite surgery the corneal pigmentation increased, and visual acuity dropped in the diseased eye. A perforating keratoplasty was performed, and two small pigmented iris nodules were now noted. Three years after grafting, growth of the two iris tumours was obvious. In addition, pigmentation of the trabecular meshwork and large, pigmented endothelial precipitates were observed. The corneal pigmentation also increased. The eye was enucleated. Histopathologic evaluation demonstrated a marked accumulation of melanophages on the endothelium of the graft. The host cornea contained pigmented cells in the mid-stroma. The iris contained two melanomas.
Conclusions: The brown pigmentation of the cornea was due to pigment granules from the iris tumours liberated to the anterior chamber. The pigment was transported into the cornea through the endothelium and accumulated in melanophages between corneal lamellas. The pigment subsequently cleared via the corneal limbus in a process resembling clearance of corneal haemochromatosis.