T-cell pseudolymphoma in recurrent herpes simplex virus infection.

In cases of herpes virus infection without typical histologic (and clinical) signs it is difficult to achieve the correct diagnosis by histology alone. Some of those cases are prone to be misdiagnosed as cutaneous lymphoma.This retrospective study included five patients with herpes simplex virus (HSV)-associated pseudolymphoma. We investigated clinical, histomorphologic and immunophenotypic features of all patients.All biopsy specimens presented a superficial and deep perivascular lymphohistiocytic infiltrate with epidermotropism, atypia and admixed plasma cells to varying degrees. Four of five samples showed lining-up of lymphocytes in the junctional zone with predominance of CD8+ lymphocytes, in contrast to the dermal part (inverse CD8:CD4 ratio). Papillary edema was found in four of five cases. Clinically, patchy erythema located on the buttocks and adjacent areas was typical, sometimes with erosions and crusts. Medical history of recurrent blisters, pain or itching was additionally helpful.We point out subtle but consistent histomorphologic criteria, which were helpful to diagnose HSV-associated pseudolymphoma in context with the clinical presentation.