Zoon Balanitis

Zoon balanitis (plasma cell balanitis, balanitis circumscripta plasmacellularis) is a benign chronic inflammatory condition of the glans penis and the inner prepuce. It affects uncircumcised, middle aged and older men (mean age about 55 to 65 years, rarely younger). It runs a chronic course with remissions and relapses and does not resolve spontaneously.

The cause is unknown. Possible factors are chronic irritation and friction within the moist subpreputial environment, trauma, poor hygiene, infection (Candida, Mycobacterium smegmatis, Treponema, Gardnerella), a tight prepuce (phimosis), obesity, and diabetes.

It is a chronic dermatosis. Histology shows:

• A dense band like infiltrate of plasma cells in the upper dermis.
• Thinned epidermis with loss of the granular layer.
• "Lozenge" keratinocytes (diamond shaped) and haemosiderin deposits.
• Dilated capillaries, which give the clinical appearance.

The condition is benign, but it must be differentiated from erythroplasia of Queyrat, which has malignant potential. Similar lesions on the vulva and lip are termed Zoon vulvitis and cheilitis.

• A solitary, well demarcated, shiny, smooth, moist, orange red to reddish brown patch or plaque on the glans and the facing inner prepuce ("kissing lesion", with matching lesions on both surfaces), often with pinpoint, cayenne-pepper-like speckles (haemosiderin).
• Usually asymptomatic or mildly itchy, with burning, soreness and tenderness, and occasional bleeding; dyspareunia.
• Mild subpreputial discharge, and a foul odour.
• Associated phimosis or foreskin tightness.
• Occasionally multiple lesions, erosions, or involving the meatus or shaft.
• Absence of induration, ulceration or lymphadenopathy (these suggest malignancy).

• Diagnosis is clinical, from the characteristic appearance. Biopsy is advised in all persistent or atypical lesions, for confirmation and to exclude carcinoma in situ.
• Punch biopsy (3 to 4 mm) of the glans shows a band like infiltrate of plasma cells (more than 50 percent) with occasional lymphocytes and neutrophils.
• Other biopsy findings are thin or ulcerated epidermis, lozenge shaped basal and suprabasal keratinocytes with spongiosis, vascular dilation and extravasated red cells, with haemosiderin. There is no dysplasia or atypia, and the plasma cells are polyclonal.
• Swabs for bacteria, Candida and sexually transmitted infections, and syphilis serology (secondary syphilis can contain many plasma cells, so it must be excluded); HIV serology.
• Blood glucose or HbA1c.
• Differential diagnoses: erythroplasia of Queyrat (squamous cell carcinoma in situ), lichen planus, lichen sclerosus, psoriasis, candidal balanitis, contact dermatitis, fixed drug eruption, reactive arthritis (circinate balanitis), and syphilis.

• Circumcision is the definitive treatment, with cure rates of 90 to 100 percent. It removes the moist environment and provides histological examination of the prepuce. It is the first line treatment in men with phimosis or recurrent or resistant disease.
• Topical therapy is for those who decline or are unsuitable for surgery. Use a potent topical corticosteroid (clobetasol propionate 0.05 percent ointment or mometasone 0.1 percent) once or twice daily for 4 to 6 weeks, tapered gradually.
• Response to topical corticosteroid is about 70 percent, with frequent recurrence after stopping.
• Combining with an antifungal (clotrimazole 1 percent cream) or antibacterial agents (fusidic acid 2 percent, mupirocin) reduces secondary infection.
• Topical calcineurin inhibitors are steroid sparing alternatives with good efficacy. Use tacrolimus 0.1 percent ointment twice daily or pimecrolimus 1 percent cream twice daily, for 4 to 12 weeks.
• Hygiene measures: gentle cleansing with water, avoiding soaps and irritants, thorough drying, and emollients (soap substitutes).
• Other options in refractory disease: topical imiquimod (limited evidence), intralesional corticosteroid (triamcinolone 10 mg/mL injected), oral antibiotics (doxycycline 100 mg daily for several weeks, in some reports), fractional carbon dioxide laser ablation, erbium:YAG laser, photodynamic therapy, and cryotherapy.
• Treat associated conditions: glycaemic control and weight loss; treat infection.
• Follow up: review after 4 to 6 weeks. Re-biopsy any lesion that does not respond or changes (induration, ulceration, warty surface). Monitor regularly those who retain the foreskin, given the small possibility of the lesion masking carcinoma in situ.
• Prognosis is excellent after circumcision, and the lesion does not undergo malignant transformation, but the mimics must be excluded.