Psoriasis Herpeticum due to Varicella Zoster Virus: A Kaposi's Varicelliform Eruption in Erythrodermic Psoriasis.

Kaposi's varicelliform eruption (KVE) or eczema herpeticum is characterized by disseminated papulovesicular eruption caused by a number of viruses like Herpes simplex virus I and II, Coxsackie virus, and Vaccinia and Small pox viruses in patients with pre-existing skin disease. The occurrence of KVE with psoriasis has been reported recently as a new entity psoriasis herpeticum. The rare causation of psoriasis herpeticum due to Varicella zoster virus in a patient with underlying psoriasis is being reported for the first time.

Introduction

Kaposi's varicelliform eruption (KVE) or eczema herpeticum is characterized by disseminated papulovesicular eruption usually caused by viruses like herpes simplex virus (HSV) I and II, coxsackie virus, and vaccinia and small pox viruses in patients with pre-existing skin disease.[1] The term eczema herpeticum, however, has conventionally been reserved for KVE caused by herpes group of viruses.[2] Various skin conditions predisposing to KVE include atopic dermatitis, seborrheic dermatitis, pityriasis rubra pilaris, Darier's disease, ichthyosis vulgaris, mycosis fungoides, neurodermatitis, pemphigus, benign familial pemphigus, irritant dermatitis, burns, lupus vulgaris and various dermatological therapeutics like skin auto-grafting, dermabrasion, BCG vaccination etc.[3] Recently, association of KVE with HSV in three patients with psoriasis has been termed as psoriasis herpeticum.[34] We report a case of psoriasis herpeticum following herpes zoster thoracis in a patient with erythrodermic psoriasis. The causation of KVE or psoriasis herpeticum due to varicella zoster virus has not been reported so far.

Case Report

A 65-year-old male with four years history of psoriasis presented with psoriatic erythroderma of two weeks’ duration. A sudden withdrawal of oral steroids (prednisolone 40 mg/day) prescribed by his family physician for last eight weeks precipitated the erythrodermic state.

After hospitalization, prednisolone 30 mg daily was again instituted in order to taper it gradually. Low dose weekly oral methotrexate (0.2 mg/kg) was started in order to manage psoriatic erythroderma. On the day 7 of admission, when erythroderma was improving, he developed acute severe neuralgic pain over left shoulder radiating down towards left arm. Within next 24 hours, herpetiform segmental vesiculopustular eruptions appeared over neck, shoulder, and inner side of left arm (C7, 8T1). The next day, patient started developing fever with chills and vesiculo-pustular lesions got disseminated all over the body. A diagnosis of herpes zoster thoracis with Kaposi's varicelliform eruption was made [Figures 1 and 2]. The differential diagnosis of Herpes simplex with Kaposi's varicelliform eruption and disseminated zoster was also considered. Routine investigations including hemogram, renal and liver function tests, chest X-ray were normal except for mild leukocytosis and raised erythrocyte sedimentation rate (ESR). A skin biopsy from papulovesicular lesions present on back was sent for histopathological examination, viral culture, and polymerase chain reaction (HSV I and II). PCR for Varicella zoster virus could not be done due to its non-availability. Histopathology revealed intraepidermal vesiculation with ballooning degeneration of keratinocytes, intranuclear inclusions, and multinucleated giant cells along with mild dermal lymphomononuclear infiltrate. PCR for HSV I and II was negative corroborating KVE due to dissemination of VZV. The patient was started with acyclovir intravenously in dose of 10 mg/kg wt. three times a day for 7 days. Vesicular lesions regressed in 1 weeks’ time while the treatment of psoriasis continued as before. No recurrence of papulovesicular or vesicular lesions was observed in segmental or disseminated form in five years of follow-up.

Figure 1

Zosteriform vesiculobullous lesions over left shoulder

Figure 2

Generalization of vesiculobullous lesions in same patient

Discussion

Kaposi's varicelliform eruption or eczema herpeticum was first described by Moriz Kaposi (1887) while describing 10 cases of vesiculopustular eruptions which he termed as eczema larvare infantum.[5] Different descriptive terms like eczema herpeticum, eczema vaccinatum, eczema molluscatum were however used later depending upon aetiological agent inducing disseminated eczematous eruptions irrespective of underlying predisposing cutaneous disease.

The exact aetio-pathogenesis of KVE is far from clear. It appears to involve a complex interplay of factors which include breach in skin barrier function in presence of dermatitis, increased susceptibility to infection due to altered host defense, demasking of binding sites for viruses, and lack of plasma cytoid dentritic cells along with failure to up regulate host antiviral proteins.[3] Eczematous skin explants of patients with atopic dermatitis and psoriasis have also been observed to have faster viral replication than normal skin, probably making them more susceptible to infection.[6]

Clinically, KVE involves spread of lesions to areas affected by another skin disease without much evidence of exogenous direct cutaneous inoculation as the nerve endings and sensory ganglions are usually not affected. Similarly, reactivation and recurrences, a hallmark of herpes group of viral infections, are not usual with KVE. Thus, dissemination of virus in KVE appears to be mainly hematogenous as evidenced by detection of HSV - DNA in non - herpetic areas of patients with KVE.[78] Diagnosis of KVE is usually clinical combined with laboratory evidence of viral infection like ballooning degeneration of keratinocytes in Tzanck smear from vesiculo-pustular eruptions along with viral cultures and PCR. A number of skin diseases predisposing to KVE have been reported, but still its association with psoriasis is rare. Recently, Rosurberger coined a new term, psoriasis herpeticum, to describe KVE with HSV in patients of psoriasis.

The present patient had an eruption clinically suggestive of Herpes zoster with dissemination akin to disseminated zoster in an immunocompromised subject. Whether erythrodermic psoriasis has contributed in the dissemination of cutaneous eruption in this patient is difficult to ascertain, but keeping in view the extent of herpetic eruption, the possibility of psoriasis herpeticum induced by Varicella zoster virus on a background of erythrodermic psoriasis is equally tenable.

A transient viremia occurs in all herpes zoster patients localized to a particular dermatome. This transient viremia is responsible for Herpes zoster with aberrant vesicles and secondary cases of varicella. However, a persistent viremia in some patients may lead to disseminated zoster especially in association with immunosupression. The present patient was receiving systemic glucocorticoids and methotrexate along with a compromised cutaneous barrier due to erythrodermic psoriasis may have acted as an ideal subject for development of disseminated zoster or KVE, both of which appear to be clinical indistinguishable in this patient.