Diagnosis: Clear cell acanthoma (Pale cell acanthoma)
Comment: A benign, slow growing nodular or plaque-like hyperplasia of the epidermis.
Location/age: Lower extremities/middle aged and elderly.
Histologically, a sharply demarcated epidermal proliferation of glycogen-rich keratinocytes. Acanthotic epidermis is composed of cells with pale-staining cytoplasm. Parakeratosis with neutrophilic keratitis. Lesional epidermis is sharply demarcated from adjacent normal epidermis. Neutrophilic infiltration in the pale lesional squamous cells.
Deba P Sarma, MD, Omaha