Zosteriform dermatoses-A review

The zosteriform distribution of cutaneous lesions is a common disease pattern in dermatology. It describes a unilateral girdle-like distribution restricted to the sensitive nerve territory of a dermatome. Three different pathogenic pathways can lead to a zosteriform pattern. The neural pathway uses the axons of a nerve ganglion for viral transport to a specific dermatome. The arche type is Herpes Zoster (HZ) followed by Zosteriform Herpes Simplex Virus Type (HSV) I infection. The Blaschkoid pathway uses the Blaschko lines that represent embryonic migration patterns, often mimicking a dermatomal distribution, particularly on the trunk. The isotopic pathway defines a dermatosis that exclusively develops on the site of a previously healed HZ eruption. Before a zosteriform eruption, a history of prior HZ guides the diagnosis to the isotopic pathway, mainly represented bygranulomatous reactions followed by, among others, lichen planus, vasculitis and basal cell carcinoma. With no prior history of HZ recent eruptions orientate towards HZ and zosteriform HSV, whereas chronic eruptions should primarily evoke cutaneous metastases, principally from breast, ovary and lung carcinoma. This review summarizes the relevant literature and presents a clinical algorithm for the differential diagnosis of zosteriform dermatoses. Introduction Pattern recognition is an important diagnostic tool in clinical dermatology. The zosteriform pattern is defined as an unilateral and belt or girdle-like presentation of a dermatosis along the sensitory nerve territory of a dermatome [1-3]. Although Herpes Zoster (HZ) is the archetype of a zosteriform dermatosis, a large series of other infectious, neoplastic, inflammatory and miscellaneous dermatoses may also present a zosteriform distribution (Table 1). This paper reviews the three pathogenic mechanisms of the zosteriform pattern and proposes a diagnostic algorithm helping the dermatologist in the differential diagnosis of zosteriform dermatoses. Materials and methods A PUBMED search was performed without restriction of publication date using the following keywords: Varicella Zoster Virus (VZV), varicella, herpes zoster, Herpes Simplex Virus (HSV), herpes simplex, genital herpes, zosteriform, zosteriform dermatoses, segmental, segmental dermatoses, dermatome, dermatomal distribution, isomorphand isotopic dermatoses. This research revealed 220 publications relevant to the subject and included for this review. Pathogenesis Cutaneous diseases presenting a zosteriform distribution answer to 3 different pathogenical pathways. The neural pathway The neural pathway is classically at the origin of HZ [1-3]. The reactivation of latent VZV infection in the neural cell bodies and the satellite cells of the Dorsal Root Ganglia (DRG) results in the replication and synthesis of new viral particles that are transported antidromically via the microtubular system of the axons to the skin. Once arrived at the free nerve endings between the basal keratinocytes and around the perifollicular free nerve endings, the viral particles egress and are captured by surface receptors on keratinocytes. Once internalized, viral replication leads to the appearance of the cytopathic effect in the host cell, finally leading to its cell death with the liberation of new viral particles. This epidermal cytopathic effect leads to the dehiscence between infected keratinocytes and intra-epidermal blister formation, responsible for the clinically observed vesicular lesions in an unilateral clustered dermatomal distribution. HZ skin lesions occupy a more or less important part of a dermatome, depending on the number of infected axons involved and afflicted by viral reactivation in the DRG. Further cutaneous extension and spreading beyond the dermatomal limits can also be due to the spread of VZV from keratinocyte to keratinocyte, especially in the immunocompromised patient or in the patient with atopic dermatitis or other predisposing skin diseases. In some instances, HZ can affect more than one adjacent dermatome. Exceptionally, more than one non-adjacent dermatomes or bilateral eruptions are encountered [4]. The unilateral character is not always respected as minor nerve projections frequently extend to the contralateral side [5]. Indeed, it was recently demonstrated that numerous dermatomal maps were inaccurate and subject to significant variations [5]. A novel evidence-based dermatome map (Figure 1) is presented with the most consistent tactile dermatomal areas for each spinal dorsal nerve root found in most individuals. In contrast to previous data, overlap and interindividual variability seem more common than previously thought [5]. Correspondence to: Prof. Dr. A.F. Nikkels, Department of Dermatology, CHU du Sart Tilman, University of Liège, B-4000, Liège, Tel: +32 4 366 7232; Fax: +32 4 366 7234; E-mail: [email protected]