The cutaneous manifestations of human parvovirus B19 infection.

The prototypical cutaneous manifestations of human parvovirus B19 (B19) infection include a petechial eruption in a glove and stocking distribution, reticular truncal erythema, and the "slapped cheek" sign. An association with connective tissue disease (CTD) stigmata has recently been made. The clinical and dermatopathologic findings in 14 patients whose skin lesions were accompanied by serological evidence of B19 infection or documentation of B19 genome in lesional skin are presented. The authors encountered skin biopsy specimens from 14 patients who presented with skin eruptions accompanied by clinical signs or serology suggestive of antecedent B19 infection. Clinical findings were correlated to the light microscopic appearance of the lesions and the presence of B19 genome in lesional skin. The study group comprised 9 women, 3 men, and 2 boys. Eruptions characteristic of fifth disease, including the slapped cheek sign, reticulated truncal erythema, and acral petechiae, were present in 3 patients, 1 of whom later developed granuloma annulare. The other patients had atypical clinical presentations comprising an asymptomatic papular eruption (2), an eruption clinically resembling Sweet's syndrome (3), myopathic dermatomyositis (DM) (2), lupus erythematosus (LE)-like syndromes (2), and lower-extremity palpable purpura (2). Skin biopsy specimens in 12 cases showed interstitial histiocytic infiltrates with piecemeal fragmentation of collagen and a mononuclear cell-predominant vascular injury pattern. Other features included an interface dermatitis, eczematous alterations, and papillary dermal edema. Lesions with features of DM or LE also showed mesenchymal mucinosis, whereas a biopsied lesion of palpable purpura showed leukocytoclastic vasculitis (LCV). Immunofluorescent testing showed a positive lupus band test (LBT) with epidermal IgG and C5b-9 decoration in 1 patient with a systemic LE-like illness, whereas the DM patients had negative LBTs and vascular C5b-9 deposition typical for DM. Skin biopsy specimens from 11 patients, including those whose presentations resembled LE and DM, were positive for B19 genome. The dermatopathology of B19 infection suggests tissue injury mediated by delayed-type hypersensitivity, by antibody-dependent cellular immunity directed at microbial antigenic targets in the epidermis and endothelium, and by circulating immune complexes in the setting of LCV. These mechanisms appear to generate a clinical and histopathological picture that recapitulates that of CTD.