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Saeed Al Wadani, Michael Mines, L. David Monroe, Charles Eberhart; Conjunctival Melanoacanthoma: A New Pigmented Conjunctival Entity. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2130. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
A range of pigmented conjunctival lesions have been described, but the nomenclature used to classify these tumors varies, and understanding of their underlying pathobiology is limited. We report the clinical and pathological features of a conjunctival lesion with both melanocytic and epithelial components that does not clearly fit into the current classification scheme of pigmented conjunctival entities. Rather, it has features similar to those of oral melanoacanthoma, benign lesions which to our knowledge have not been previously reported on the ocular surface.
Histopathological and immunohistochemical evaluation of the lesion was performed in the Johns Hopkins surgical pathology laboratory using standard techniques.
The lesion arose on the perilimbal conjunctiva of a 48 year old African American man as a solitary, well defined, reddish movable plaque concerning for malignancy. On microscopic examination, the lesion was characterized by thickened epithelium with downward growth of epithelial nests and strands highlighted by cytokeratin immunostains. Dense chronic inflammation was present below the lesion. Diffusely admixed with the epithelial elements were an increased number of melanocytes immunoreactive for MITF, MART-1, S100 and HMB-45. Many of these appeared bland, dendritic and localized to the epithelial base, but pagetoid spread and more compact cells were also noted. Ki67 revealed proliferation in both the epithelial and melanocytic components.
The microscopic features of this case do not clearly conform to the existing classification of pigmented conjunctival lesions. It thus challenges current understanding of the pathophysiology of this class of entities, and raises questions regarding appropriate clinical care. Interestingly, the lesion appears highly similar to oral melanoacanthoma, a rare benign pigmented lesion of the oral mucosa generally seen in black patients, and characterized by proliferation of both keratinocytes and HMB-45 immunoreactive dendritic melanocytes. To our knowledge, conjunctival melanoacanthoma have not been previously reported. Melanoacanthoma are benign, but our conjunctival lesion has features which overlap with primary acquired melanosis with atypia or melanoma in situ. Recognizing the potential of melanoacanthoma to arise on the bulbar conjunctiva therefore may alter the diagnosis and treatments of patients with these lesions.
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