Lichenoid benign keratosis.

A histopathologic study of 108 lesions of lichenoid benign keratosis from 104 patients confirmed previously observed clinicopathologic features such as involvement of whites, age range of 35 to 65 years, female predominance, single keratosis, common location on the arm or presternal area, and failure of clinical recognition of the lesion. Histologically, lichenoid benign keratosis can be diagnosed by the characteristic lichenoid appearance, parakeratosis, an infiltrate occasionally containing plasma cells and eosinophils, and remnants of lentigo-like changes at the periphery of the lesion. The clinical information of a solitary lesion and suspicion of a premalignant or malignant diagnosis aids in establishing the pathologic diagnosis of the disease. Direct immunofluorescence studies of tissue from seven lesions of lichenoid benign keratosis resembled those seen in lichen planus. Features distinguishing lichenoid benign keratosis from lichenoid solar keratosis are discussed.