Balanitis of Zoon: a clinicopathologic study of 45 cases.

Balanitis of Zoon is a relatively common diagnosis in elderly men, although its nature is controversial and descriptions of its histopathologic features in current textbooks of dermatopathology vary considerably. We studied 45 cases of balanitis of Zoon clinically and histopathologically. The earliest histopathologic changes in cases diagnosed clinically as balanitis of Zoon were slight thickening of the epidermis, parakeratosis, and a patchy lichenoid infiltrate of lymphocytes and some plasma cells. More advanced cases showed atrophy of the epidermis, superficial erosions, a scattering of neutrophils in the upper reaches of the epidermis, scant spongiosis, extravasation of erythrocytes, and a much denser infiltrate with many plasma cells. Additional findings at even later stages were subepidermal clefts, sometimes with loss of the entire epidermis, marked fibrosis of the superficial dermis, and many siderophages. That sequence of histopathologic changes is compatible with the thesis that balanitis of Zoon results from irritation or mild trauma affecting barely keratinized skin in a moist environment. As a reaction to nonspecific stimuli, balanitis of Zoon may be found superimposed on lesions of other diseases and may modify the histopathologic presentation of those diseases to the extent that they are no longer recognizable. In the current study, several cases diagnosed originally as balanitis of Zoon turned out to be examples of allergic contact dermatitis, psoriasis, lichen planus, and squamous cell carcinoma in situ. It is important, therefore, to recognize balanitis of Zoon as a nonspecific pattern that may occur either as an isolated finding or may complicate other diseases affecting the glans penis or prepuce of uncircumcised men.