In our case, the distinctive features were the polymorphous eruption on the face and trunk, the monomorphous tender pustules on the palms and soles and the painful oral erosions. The skin lesions on the face and trunk showed multiple-staged papules, vesicles, pustules and crusts and these showed clinical improvement during the antiviral treatment. However, the tender pustules on the palms and soles were not improved or crusted 3 days later after starting antiviral treatment. The pustular eruption on the palmoplantar area was considered for making the differential diagnoses of atypical varicella, hand-foot-mouth disease, erythema multiforme and localized pemphigoid. We excluded localized pemphigoid because of its rare childhood presentation, its predilection for flexural areas and the subepidermal blisters that were without reticular degeneration6
. In contrast to our case, erythema multiforme shows typical targetoid lesions on the extensor surface of the extremities and it is triggered by a preceding infection with herpes simplex virus or by drugs7,8
. The histopathologic findings of erythema multiforme also exhibit spongiosis, vacuolar degeneration of the basal cell layer with satellite cell necrosis, and focal junctional and subepidermal cleft formation8
The form of varicella that occurs most often in childhood is an acute, highly contagious exanthem that exists simultaneously with all stages of the skin lesions. The varicella with unusual clinical aspects and an unusual course is referred to as atypical varicella, and this is characterized by an unusual distribution and/or a prolonged course4,9
. Atypical varicella has been associated with pre-existing factors such as an immunocompromised status, sun exposure, local injury and preexisting rash4,9
. Our case was a healthy child without atopic dermatitis, recurrent infection or a history of trauma. The clinical features of our case were not consistent with varicella, and especially the painful oral erosion as well as the tender nonpruritic monomorphous pustules on the palms and soles. In contrast, Tzanck's test from the vesicles of the abdomen showed multinucleated giant cells, and the skin biopsy from the pustules of the palm showed only reticular degeneration without inclusion bodies or multinucleated giant cells. A serologic test was positive for IgM varicellazoster antibody and there was an elevated level of Coxsackievirus A16 antibody, although we didn't perform follow-up serologic testing. There was no clinical improvement of the palmoplantar lesions in contrast with that of the trunk and face. Based on the above evidence, we thought that our case was varicella coinfected with hand-foot-mouth disease.
Auvin et al4
have described atypical varicella with palm and sole involvement that showed the same stage of evolution with positivity for both IgM and IgG varicella-zoster antibodies and positivity for IgG B1-coxsackie antibody without IgM. They suggested that the intraepidermal lesions were caused by a pre-existing B1 coxsackie infection, meaning that subclinical hand-foot-mouth disease might explain the distal involvement in the cases of atypical varicella.
Our present case is a unique case that probably confirmed Auvin et al's explanation of varicella combined with hand-foot-mouth disease, as was proven by the serologic testing, Tzanck's test and the histopathologic examination. Varicella can be associated with a variety of diseases even in healthy persons. So clinicians must be aware of the atypical clinical manifestations of varicella and they must consider the involvement of concomitant disease such as a coinfection of virus or bacteria and blistering dermatitis3,4