Histopathologic features of cutaneous herpes virus infections (herpes simplex, herpes varicella/zoster) - a broad spectrum of presentations with common pseudolymphomatous aspects

Cutaneous eruptions caused by herpes simplex 1/2 (HSV-1/2) and herpes varicella/zoster (VZV) represent common dermatoses. In some cases, they present with atypical clinical and/or histopathologic features, including presence of dense lymphoid infiltrates with atypical lymphocytes simulating cutaneous lymphomas. In this study, we reviewed the biopsy specimens of 65 patients (33 males, 32 females; mean age, 61.2 years; median age, 62 years; age range, 19-96 years) with cutaneous eruptions caused by HSV-1/2 or VZV Histologic examination revealed several atypical findings, including presence of dense lymphoid infiltrates, angiotropism, and atypical lymphocytes simulating malignant lymphoma. Immunohistochemistry performed in 22 cases showed a predominant T-cell infiltrate, in the majority of cases with variable numbers of CD30+ and CD56+ cells. Two cases with a pseudolymphomatous appearance and small clusters of CD30+ cells revealed a monoclonal population of T lymphocytes by PCR analysis, underlying the difficulties in classifying some of these cases correctly. Our study indicates that cutaneous herpes infections can exhibit several atypical histopathologic, immunohistochemical, and molecular features, and that in given cases accurate clinicopathologic correlation and short-term follow-up controls are necessary for differentiation from cutaneous lymphomas.