An uncircumcised 58-yearold man presented with a persistent “rash” on his penis of 5 years’ duration. He complained of localized irritation with coitus. Over-the-counter ointments and corticosteroid preparations had failed to clear the eruption. The patient had hypertension, hyperlipidemia, and coronary artery disease. He had been monogamous for the last decade and denied any risk factors for sexually transmitted diseases. Drs Frank T. Armstrong, Richard A. Miller, Michael E. Krutchik, and David W. Dorton of Largo, Fla, noted a discrete, glistening erythematous plaque on the patient’s glans penis. Penile discharge, ulcerations, and adenopathy were absent. The ocular and oral mucosa were unaffected. A review of systems revealed no significant findings. A punch biopsy was performed after the lesion failed to respond to a trial of ciclopirox olamine and triamcinolone acetonide 0.01% creams (A and B). Histopathologic findings were consistent with Zoon’s balanitis. Culture of the penile plaque revealed normal commensal flora. Serologic tests ruled out HIV infection and syphilis. The cause of Zoon’s balanitis is unknown. Other names for the disease are plasma cell balanitis, balanitis circumscripta plasmacellularis, and plasma cell mucositis. In women, this condition is called plasma cell vulvitis. Zoon’s balanitis presents most often as a solitary, glistening, red or cayenne pepper–colored, persistent plaque on the glans penis or inner surface of the prepuce of an uncircumcised, middle-aged or older man. The usually asymptomatic lesion can be mildly pruritic and may become irritated with intercourse. Secondary candidal infections are not uncommon. The differential diagnosis includes infection with Candida albicans, groups A and B streptococci, Gonococcus, Gardnerella vaginalis, Trichomonas vaginalis, mycoplasma, and Chlamydia trachomatis; genital herpes; syphilis; nonspecific intertrigo; traumatic lesions; psoriasis vulgaris; Reiter syndrome; allergic contact dermatitis; fixed drug eruption; and drug-induced erosions. Squamous cell carcinoma and extramammary Paget disease need to be considered as well because Zoon’s balanitis can resemble a malignancy. Note that isolated cases of penile carcinoma preceded by Zoon’s balanitis have been reported. Diagnosis is based on histologic findings. Often, the failure of empiric topical corticosteroids and antifungals prompt a biopsy to rule out neoplasia. Histologically, the epidermis appears thinned, often showing an absence of the upper layers. In this setting, the thinned epidermis is flattened and composed of diamond-shaped, pancake- like keratinocytes that are separated by uniform intercellular edema. It is not uncommon for erythrocytes to percolate up through the epidermis. The upper dermis demonstrates a lichenoid infiltrate with copious plasma cells; however, in some patients, the number of plasma cells is low. Capillary dilatation also is not uncommon. Mild topical corticosteroids are used initially; however, the disease often recurs when the preparation is discontinued. Although laser therapy is an option, circumcision remains the treatment of choice because it is curative in nearly all cases. Close follow-up to monitor the patient for a recurrence is recommended. After extensive counseling, this patient was referred to a urologist for circumcision.
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