Background Genital lesions lead patients to seek care in sexually transmitted diseases (STD) clinics. The old axiom “all genital lesions must be considered sexually acquired until proved to the contrary” is true today. A high level of suspicion of an STD must accompany examination of patients with genital lesions. Although other causes are also seen, we present a case of Zoon’s balanitis in a patient with HIV infection.

Methods A 40-year old, white male, sought attention for a genital lesion evolving over six months. He was on treatment with antiretrovirals, and underwent treatment with topic and systemic antifungal without improvement. He had multiple, well-delimited, moist red-orange lesions on the glans and foreskin. Some lesions had a face-to-face (kissing) disposition. Treponemal and non-treponemal serology was negative. With the hypothesis of plasmacytic balanitis, a biopsy was performed. Histopathologic examination demonstrated a lichenoid inflammation with an inflammatory infiltrate with plasmocytes, lymphocytes and neutrophils. No vascular alteration was found. There was spongiosis and erosion of the epithelium.

Results Zoon balanitis is a chronic, idiopathic, reactive balanoposthitis. It is believed to be associated with irritation in the context of a dysfunctional foreskin. It presents as well-circumscribed orange-redish moist lesions in the glands and foreskin, usually asymptomatic. HIV infection is an acknowledged risk factor for other STDs. Infectious causes such as candidiasis and syphilis are much more common and must be considered. Syphilitic lesions and Zoon balanitis share clinical and histopathological features including a slight thickening of the epidermis, parakeratosis, and patchy lichenoid infiltrates of lymphocytes and plasma cells, making their differential diagnosis complex, hence the need of always performing syphilis serology in such cases.

Conclusion In spite of STD generally being the first hypothesis in patients with genital lesions, many causes must be considered, especially when atypical lesions are present or there is poor response to therapeutic measures.

Disclosure No significant relationships.