p16+ Squamous cell carcinoma in situ masquerading as genital psoriasis

HPV: human papilloma virus MGUS: monoclonal gammopathy of undetermined significance PIN: penile intraepithelial neoplasia SCCIS: squamous cell carcinoma in situ INTRODUCTION Cutaneous neoplasms of the male genitalia are an important consideration in older men and immunocompromised patients. They are derived from the squamous epithelium and have an association with human papilloma virus (HPV). HPV types 16, 18, and 57b have been isolated, and their DNA is present in approximately 40% to 45% of all penile carcinomas. Squamous cell neoplasia includes both squamous cell carcinoma in situ (SCCIS) and invasive carcinoma. Risk factors include increasing age, immunosuppression, smoking, exposure to ultraviolet light, benzene, and arsenic. Invasive squamous cell carcinoma is uncommon in the genital region. It may advance from SCCIS or present as a more aggressive tumor. In general, both invasive squamous cell carcinoma and SCCIS canpresent as erythematouspatches or plaques with or without significant scale on the penis and inguinal skin. Many conditions mimic SCCIS in the inguinogenital region. Intertrigo, psoriasis, dermatophytosis, candidiasis, Darier disease, Hailey-Hailey, plaque stage cutaneous T-cell lymphoma, and extramammary Paget disease can all resemble SCCIS. Genital psoriasis, in particular, is underrecognized. Involvement of the genital area occurs in 29% to 46% of all psoriasis patients. The symptoms of genital psoriasis are mild to moderate, with itch, pain, and burning most commonly reported. These symptoms closely mimic those of SCCIS. Scale is often absent in genital psoriasis. Here we report a case of SCCIS that closely resembled genital and inverse psoriasis. The tumor