Facts about skin from the New Zealand DermNet Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Herpes simplex, varicella zoster and herpes infections show identical histology. Clinical correlation or immunohistochemistry and / or viral culture or PCR (of an Appropriate swab or tissue specimen) is required to differentiate viral infections in Original. Histology of herpes infections The histology of herpes infections is very distinctive. The low power pattern of a typical lesion is of an intraepidermal blister (Figure 1). The key feature is acantholysis With solitary Within the blister cavity keratinocytes (Figures 1, 2, 3). Keratinocytes will show the viral infection of nuclear Changes. These included margination of the nuclear chromatin, multinucleation and nuclear inclusions (Figures 3, 4, 5). The viral inclusions are small pink deposits with a clear halo seen Within the nucleus. When present in herpes virus infection and present With The Changes of other nuclear esta infection Cowdry They are called Type A inclusions. Cowdry Type B inclusions are Associated With other infections: such as polio virus and do not Have the other nuclear Changes of herpes infection.
Early Changes of vacuolation in the cytoplasm May be seen along the basal keratinocytes. As the cells swell and separate, the eosinophilic cytoplasm Becomes remarkable Particularly in the multinucleated cells. The inflammatory infiltrate is mixed, lymphocytes and neutrophils Predominantly With faq frequently seen scattered eosinophils (Figure 6). Histological variants of herpes infections Herpes folliculitis: Changes In This variant can be subtle and HENCE Particularly in early Easily overlooked lesions or When the follicle is only partially Represented. The key finding is of a necrotic hair follicle With An Associated dense surface and deep lymphocytic infiltrate With neutrophils. Typical viral Changes can be seen in acantholytic epithelial cells of the infundibular region Predominantly Involved in or adjacent epidermis. Verrucous varicella zoster and herpes: In this variant there is hyperkeratosis and epidermal acanthosis prominent in Addition to the viral cytopathic changes. Special tests in herpes infections Immunoperoxidase staining by monoclonal antibody is available to herpes simplex types 1 and 2 and to varicella zoster. It is possible to perform PCR Present and / or an Appropriate culture specimen to distinguish Between Both herpes simplex viruses and the herpes zoster. Differential diagnosis of herpes infections Coxsackie virus infection / hand foot and mouth disease: Blisters show intraepidermal vesiculation and acantholysis nuclear inclusions or without multinucleation.
Pemphigus vulgaris: Clinically These conditions would rarely be confused. With NOTED acantholysis suprabasal vesicle formation is in advanced lesions, and small numbers of cells are seen acantholytic Within esta space. Viral Changes are lacking. However, it Should be disseminated herpes simplex That NOTED infection (Kaposi’s varicellifom eruption) pemphigus vulgaris can complicate virus. In troublesome cases immunofluorescence studies are decisive but IF NECESSARY Usually the additional special studies NOTED above May Also be used. It is worth Noting a number of conditions That Have Been Reported to Arise in the site of prior herpes zoster infection. These include chronic lymphocytic leukemia, granuloma annulare, lichen planus, keloid scarring, vasculitis, sarcoidosis, morphea, lymphoma and skin cancers. The acute viral infection of Changes are evident Usually not. Related information References: Skin Pathology (2nd edition, 2002). Weedon D Pathology of the Skin (3rd edition, 2005).
PH McKee, J. Calonje JE, Granter SR On DermNet NZ: Books about skin diseases: See the DermNet NZ bookstore Author: Dr Ben Tallon, Dermatologist / dermatopathologist, Tauranga, New Zealand.