Atypical lymphoid infiltration occurring at the site of a healed varicella zoster infection

Mycosis fungoides occurring at the site of previous herpes zoster eruption

Numerous clinicopathological variants of mycosis fungoides have been described in the literature. Dermatomal or zosteriform mycosis fungoides is one reported variant but a clear aetiology has never been documented. We report a case of mycosis fungoides proved by biopsy and immunohistochemistry that developed in a 55-year-old man at the site of previous herpes zoster eruption. We also present a review of the relevant literature to add to the understanding of rare variants of mycosis fungoides and aid in the clinical recognition of zosteriform mycosis fungoides.

Herpes zoster granulomatous dermatitis: histopathologic findings in a case series

Several types of cutaneous reactions have been reported to arise at the site of herpes zoster (HZ) infection weeks to years after the acute disease. Among these, granulomatous reactions are the most frequently reported. In this study, we describe the spectrum of histopathologic findings of HZ granulomatous reactions observed in 26 patients with cutaneous lesions confined to the area of previous HZ eruption and compare them with biopsy specimens taken from 25 patients with acute HZ. All patients with persistent reactions from whom history was available presented within 12 weeks of the onset of the acute eruption. The most frequent findings were interstitial granulomatous dermatitis with lymphocytes, histiocytes and multinucleated giant cells displaying elastophagocytosis and a perineural, perivascular and perieccrine mononuclear inflammatory infiltrate rich in lymphocytes and plasma cells. Less common features included intra-arrector and peri-arrector pili granulomas, follicular dilatation and hyperkeratosis, and vasculitis. Specimens from patients with acute HZ were found to have small numbers of perineural plasma cells and most had subtle granulomatous inflammation, in patterns similar to the group with late granulomatous reactions. Our findings suggest that granulomatous reactions to varicella zoster virus represent a persistent evolving inflammatory reaction after acute infection.

Varicella-Zoster-Virus Folliculitis Promoted Clonal Cutaneous Lymphoid Hyperplasia

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).

Resistance to Activation-Induced Cell Death and Bystander Cytotoxicity Via the Fas/Fas Ligand Pathway Are Implicated in the Pathogenesis of Cutaneous T Cell Lymphomas

By engaging Fas, Fas ligand (FasL) on activated T lymphocytes induces activation-induced cell death (AICD), and also triggers apoptosis of target cells during immune downregulation. We previously showed that within cutaneous T cell lymphoma (CTCL) lesions, malignant CD4(+) T cells expressing FasL accumulated, and were inversely distributed with CD8(+) T cells. We thus determined the responses of human CTCL cells to AICD and their cytotoxic to Fas(+) target T cells in vitro. CTCL cells expressing Fas were resistant to AICD following activation by CD3 monoclonal antibody (mAb) whereas still undergoing apoptosis if Fas was ligated to Fas mAb. CTCL cell lines, as well as Sezary Syndrome patients' peripheral blood lymphocytes, exhibited ratio-dependent cytotoxicity to Fas(+) Jurkat cells. The kinetic study showed that FasL surface expression was absent before activation, and its expression was low and/or delayed after activation. We therefore hypothesize that CTCL cells express functional FasL possibly contributing to bystander cytotoxicity within tumor infiltrates. In addition, decreased and/or delayed FasL surface expression following activation may in part contribute to their resistance to AICD. Both bystander cytotoxicity and resistance to AICD are likely to contribute to the loss of cytotoxic anti-tumor CD8(+) T cells as well as the accumulation of malignant T cells in CTCL.