Ocular Pathology

Anatomy and pathology of the human eye. Use it to review eye pathology for Ophthalmology Board Review or OKAP.

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Wednesday, November 30, 2005

Freckle (the answers)

The eyelid freckle is characterized by the presence of increased amount of brown pigment (melanin) in the basal layers of epithelium (1). Note the cells of pigment are not melanocytes but rather epithelial cells. If the cells were all melanocytes an entirely different differential diagnosis becomes operative. There are also pigment containing melanophages (2) in the dermis and a superficial chronic perivascular dermatitis with lymphocytes and rare plasma cells (3). Freckles show hyperpigmentation of the basal layer but no elongation of the rete ridges as seen in lentigo simplex. Histologic evidence suggests that the actual number of melanocytes in freckles is decreased compared to normal adjacent epidermis. However, the melanocytes that are present in freckles have more intricately branched dendritic processes. This histologic picture may be quite difficult to distinguish from normal skin of pigmented individuals by light microscopy alone. However, the clinical appearance of discrete macules that are small and brown and generally deepened in sun-exposed areas is characteristic.

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