Herpes Zoster Granulomatous Dermatitis: A Rare but Memorable Complication

Abstract

There have been reports of benign and cancerous cutaneous reactions developing at the site of resolved herpes zoster weeks to years after the acute infection. This case study describes a 71-year-old male patient with herpes zoster granulomatous dermatitis, a manifestation of postherpetic isotopic response. His medical history was significant for Graves' disease and chronic myelomonocytic leukemia. After presenting to the emergency department, he was diagnosed with herpes zoster generalisatus. Approximately two months after receiving treatment for herpes zoster, multiple firm subcutaneous nodules appeared on his neck. An excisional biopsy was performed to rule out leukemia cutis. The specimen displayed extensive dermal lymphohistiocyte infiltration, marked by central necrosis and atypical T cells. Tests for tuberculosis and leukemia were negative. At follow-up, an excisional biopsy of the recurrent neck nodules confirmed diffuse dermal infiltration and central necrosis. Based on the clinical and pathological findings, he was diagnosed with herpes zoster granulomatous dermatitis. He was administered systemic and topical steroid therapy over one month, after which the lesions and associated symptoms improved. Wolf's isotopic response refers to the occurrence of a new skin disease at the site of an already healed, unrelated skin disease. This phenomenon is frequently overlooked—especially following herpes zoster. Healthcare practitioners should know Wolf's isotopic response to ensure accurate diagnosis and avoid potential oversight of malignant diseases.