Kaposi`s varicelliform eruption in a case of pustular psoriasis

INTRODUCTION

Kaposi`s varicelliform eruption (KVE), is a viral infection that arises in pre-existing skin conditions. The true incidence of KVE is not accurately known, because of its rarity and a lack of large studies. As the name implies, the vast majority of KVE cases are caused by herpes simplex viruses (HSV 1 and 2) and occur concomitantly with atopic dermatitis.¹ However, Cocksackie virus A16 and vaccinia virus have also been implicated. Multiple skin disorders have been associated with KVE including, pemphigus, Darier disease, psoriasis vulgaris, pityriasisrubrapilaris, Hailey-Hailey disease etc.² Occurrence of KVE in cases of psoriasis is very rare and is called as Psoriasis Herpeticum.

CASE REPORT

A-43-year-old male psoriatic patient, who has been on various topical and systemic modalities of therapy since 14 years. He had little respite in his symptoms in view of his poor compliance. The last known medication was an alternative form of medicine taken from a local homeopath. He presented to the OPD with fever and generalised erythroderma of 2 weeks duration.

On examination, he was febrile and found to have generalised erythematous scaly plaques superimposed with micropustules which were coalescing at places forming lakes of pus. The lesions were distributed symmetrically over the extremities and the trunk (Figure 1). His skin biopsy confirmed the diagnoses of pustular psoriasis (Figure 2 A and B). He was initially put on oral cyclosporine in the dose of 5 mg/kg and then tapered gradually over a period of 6 weeks and subsequently put on maintenance therapy with oral acitretin 25 mg once daily. He showed a satisfactory response with resolution of all the pustular psoratic lesions and erythroderma. On the 3^rd week of therapy, patient developed umbilicated papulo-vesicular lesions over the face, trunk and extremities (Figure 3). Few crusted plaques were also present on the trunk. A suspicion of KVE was made and a Tzanck smear was taken from one of the vesicular lesions. The smear showed the presence of multi-nucleate giant cell which confirmed the diagnoses of KVE (Figure 4). He was put on a course of oral acyclovir 400 mg thrice daily for 15 days. Patient started showing clearing of the lesions by 5^th day of therapy and there was complete resolution of the lesions by 15 days.

DISCUSSION

Kaposi varicelliform eruption was first described and reported by Moritz Kaposi in 1887.³ Kaposi’s varicelliformeruption refers to a disseminated cutaneous infection with herpesvirus type 1 or 2, vaccinia virus, or coxsackievirus A16 in a patient with another underlying dermatosis. Predominantly seen in adult patients suffering from certain skin disorders like underlying atopic dermatitis, but has also been shown to occur in patients with Ichthyosis, pemphigus, mycosis fungoides etc.² Incidence of KVE in psoriasis is rarely reported, handful cases of KVE in psoriasis have been reported till date.^2,5

KVE usually begins as clusters of umbilicated vesiculo-pustules on skin affected by a pre-existing dermatitis and may be accompanied by a flu-like syndrome of fever, chills, and malaise. The upper body is the most common site of infection, with a predilection for the head and neck. Despite the typical finding of recurrent HSV disease following an isolated dermatomal pattern; in the setting of a diffuse dermatologic condition such as psoriasis, spread across multiple dermatomes can be seen, presumably via cross contamination and inherent tissue susceptibility.⁴ 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.^6,7

The diagnosis of KVE is mainly clinical, although several laboratory tests can be useful. A Tzanck smear is the fastest test but is neither sensitive nor specific for HSV infection.⁸ Direct fluorescent antibody staining allows rapid and accurate diagnosis, with results often available in a few hours. Viral culture is both sensitive and specific for HSV infection, but takes at least 48 hours. Both biopsy and serology are of little diagnostic value, and are not recommended on a routine basis. Early use of both antiviral drugs is extremely important; their use should not be delayed pending laboratory tests. The most commonly used antiviral drugs are the nucleoside analogues, which inhibit viral DNA polymerase. Initial treatment is generally with acyclovir, the most widely studied and used drug in KVE. Valacyclovir is also very effective, with better oral bioavailability and a more convenient dosing schedule for patients.

CONCLUSION

Pusutular psoriasis is itself a rare complication of psoriasis. Developing KVE in a case of pustular psoriasis while on therapy is further a rare entity. The aim of presenting this case is to apprise the treating physicians of the myriad of complications and presentations which a case of psoriasis can present with. Both timely diagnoses and treatment with the use of appropriate lab tests will help in timely intervention and cure.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

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