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Abstract: Patients with eosinophilic pustular folliculitis (EPF), a sterile eosinophilic infiltration of hair follicles, often present with papulopustules that tend to form annular plaques. Histopathologic examination revealed eosinophilic infiltration around the pilosebaceous units and eosinophilic microabscess formation. Although the pathogenesis of EPF is unknown, T-helper type 2 immune responses were suggested to be important based on their stimulating effect on the sebaceous glands. Here, we report the first case of EPF associated with herpes zoster, indicating that herpes zoster and EPF are correlated with T-helper type 2 immune responses., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Herpes virus infections presenting as folliculitis are uncommon. We describe a 48-year-old white man with a distant history of a childhood gastric lymphoma and renal cell carcinoma presenting with an itchy eruption. He was concerned about recurrence. A punch biopsy revealed interface dermatitis with a dense atypical superficial and deep perivascular and periadnexal lymphohistiocytic infiltrate with occasional eosinophils extending to the subcutis, with destruction of vessel walls. It was composed of predominantly CD3-positive lymphocytes with scattered CD56-positive cells and CD20-positive cells, concerning for lymphoma. A T-cell gene rearrangement study was negative. Deeper sections uncovered multinucleated giant keratinocytes in the follicular epithelium of 1 hair follicle, consistent with herpes folliculitis. Cutaneous herpes infections can exhibit several variable clinical and histopathological features. Knowledge of alternative presentations of herpes infections, histological clues to the presence of herpes infections, and careful clinicopathological correlation are necessary to differentiate herpes infections from cutaneous lymphomas and other inflammatory dermatoses.

Post herpes zoster (HZ) reactions have been associated with panoply of neoplastic, inflammatory, and fibro-inflammatory cutaneous disorders. Varicella zoster virus (VZV) DNA has not been identified in most of these reports. After an episode of HZ, a healthy, active 90-year-old female developed ulcerative nodules in the affected trigeminal V1 dermatome and the contra-lateral trigeminal region over a 1-year period. Excision and/or biopsy of all these lesions showed similar pathologic changes that consisted of herpetic folliculitis, adjacent dense mixed nodular lymphocytic infiltrates with germinal centers (cutaneous lymphoid hyperplasia (CLH)), and in the deeper excision specimens, an obliterative vasculitis of a vessel with smooth muscle in its wall. Immunophenotype analysis revealed a mixed, predominate T- and B-cell population without loss of pan-T cell antigens or aberrant expression by B cells of T-cell antigens. Polymerase chain reaction for herpetic DNA was positive for VZV DNA. Lymphocyte gene rearrangement analysis revealed 2 distinct, anatomically and chronologically, monoclonal B-cell populations and a monoclonal T-cell population in one nodule. Treatment with valacyclovir has lead to almost complete resolution of her cutaneous nodules after 6 months of therapy. In this case, it can be surmised that persistence of VZV infection and lack of effective cell-mediated immunity lead to development of both immunopathology (vasculitis) and excessive lymphoid cell proliferation (CLH).

The histopathological changes of herpes simplex, herpes zoster, and varicella are considered to be indistinguishable from one another. Evaluation of the clinical setting, with adjunctive studies if necessary, generally clarifies the specific diagnosis. Vesicular lesions in all three conditions can involve epidermal and adnexal epithelium with characteristic cytopathic features. We describe three patients with non-vesicular eruptions on the head and neck whose biopsies revealed exclusive folliculosebaceous involvement by herpes. All three patients developed typical herpes zoster within days of the biopsy. There is compelling scientific evidence in the literature indicating that, in herpes zoster, the virus is transported from dorsal root or trigeminal ganglia via myelinated nerves to the skin. These terminate at the isthmus of hair follicles and primary infection of follicular and sebaceous epithelium occurs. Spread of infection to the epidermis follows. In contrast, data pertaining to recurrent herpes simplex indicates that axonal transport of the virus from sensory ganglia to the skin is directed primarily to the epidermis, via terminal non-myelinated nerve twigs. The clinical evolution of our three cases and scientific data in the literature indicate that exclusive folliculosebaceous involvement by herpes, in the setting of a non-vesicular eruption, represents early herpes zoster.