Plasmacytoid (CD68+CD123+) Monocytes May Play a Crucial Role in the Pathogenesis of Hydroa Vacciniforme: A Case Report

Abstract

Hydroa vacciniforme (HV) is a rare, blistering, childhood photodermatosis that heals with smallpox-like scars, is associated with latent Epstein-Barr virus (EBV) infection, and spontaneously resolves by early adulthood. Cytotoxic T cells are suspected to mediate the histologic hallmark of HV-dense, perivascular, lymphocytic infiltrates and reticular degeneration and necrosis of the epidermis. We report a case of 13-year-old white girl with EBV-associated HV, whose lesional skin harbored a predominate CD68, CD123 infiltrate of plasmacytoid monocytes (PMs). Other significant pathologic attributes included abundant non-neutrophilic nuclear debris, necrosis of adnexal structures, lymphocytic vasculitis, and clusters of CD30 cells. PMs produce large amounts of type I interferon during viral infection, which induces apoptosis of some cell types and promotes the survival of others. This antiviral response can explain these aforementioned pathologic findings representing wide spread cell death and lymphoid proliferation, as well as eventual resolution of HV with time, via elimination of latent EBV-infected cells. The destruction of adnexal structures can account for the depressed circinate scars characteristic of HV. The validity of this proposed mechanism must be evaluated by first examining the prevalence and number of PMs in future case series of HV.

EBV-associated Cutaneous NK/T-cell Lymphoma

“…Iwatsuki et al 23,26 and others 42,60 showed that both typical and atypical lesions of HV were characterized by the infiltration of EBER-positive T cells, suggesting that they might represent different disease stages across the same spectrum of EBV-associated cutaneous disorders. 26,59 The immunophenotype of HVLL establishes a close relationship with nasal-type extranodal NK/T-cell lymphoma, but this disease usually affects older patients (median age, 50 y) with involvement of the nose, nasal sinuses or the mouth, and the clinical course is highly aggressive with a median overall survival of 8 months, especially for those cases with extranasal involvement and advanced stage disease at diagnosis. 3,45 Primary cutaneous gd-T-cell lymphoma accounts for less than 1% of all cutaneous T-cell lymphomas.…”

Dermatomyositis and Type 1 Interferons

“…pDCs may express CD4 [24] and be mistaken for T-helper cells, may express CXCR3 [33] and be mistaken for lymphocytes, or may express CD68 [34] and be mistaken for macrophages. Conversely, pDCs and endothelial cells express CD123, so care is required in interpreting CD123 immunoreactive material as pDCs [24].…”

Tumoral aspects of plasmacytoid dendritic cells: What do we know in 2009?

“…It has been demonstrated that PDCs could appear or be increased in number, in tissues affected by variable pathological conditions: granulomatous lymphadenitis [9], Kikuchi lymphadenitis [10], Castleman's [11], Hodgkin's [12] disease or in allergic rhinitis [13]. More recently, PDCs have been found in skin of patient with psoriasis, lupus erythematosus [14], or hydroa vacciniforme [15].…”