Abstract

Herpes vegetans (HV) is a rare presentation of herpes simplex virus (HSV) infection which often occurs in the anogenital region of immunocompromised patients (most commonly in human immunodeficiency virus [HIV] infection but also reported in organ transplant recipients, malignancy, and primary immunodeficiency syndromes). It is characterized clinically by atypical hypertrophic plaques, frequently resembling verrucous or malignant lesions. We report the case of a 54-year-old male with a history of chronic HIV and anal intraepithelial neoplasia with high-risk HPV who underwent excision of a 2.5 cm pink, verrucous gluteal cleft plaque; the clinical differential diagnosis was squamous cell carcinoma (SCC) versus condyloma. Histologic sections showed hyperkeratosis, papillomatous acanthosis, focal ulceration, and prominent pseudoepitheliomatous hyperplasia with mild keratinocyte atypia. The dermis was filled by an exuberant inflammatory infiltrate composed predominantly of plasma cells and lymphocytes with scattered neutrophils and eosinophils. Close inspection of ulcerated foci revealed rare multinucleated keratinocytes with chromatin margination, nuclear molding, and intranuclear inclusions. Immunohistochemical stains for both HSV-1 and HSV-2 were positive within these cells. Additional stains to rule out a coexisting infection or plasma cell neoplasm (PCN) were negative and the overall findings were consistent with HV. Due to the rarity and atypical clinical and histologic appearance of HV, initial diagnostic considerations may include SCC, PCN, and other infectious processes (including condyloma acuminatum and condyloma latum). Pathologists should be familiar with this entity to avoid misdiagnosis and facilitate appropriate clinical management. Knowledge of its unique presentation is key, but additional clues to the diagnosis include a history of immunocompromise and a careful search for viral inclusions, especially in the vicinity of ulcers.

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