Parvovirus B19 Infection

Abstract

Parvovirus B19 causes the common childhood exanthem erythema infectiosum (fifth disease) and less common skin eruptions including urticaria, a vesiculopustular rash, purpura with or without thrombocytopenia, Henoch-Schönlein purpura, and a “gloves and socks” acral erythema with or without papules. Associated findings that may suggest B19 as the etiological agent include recent known community outbreak; sudden-onset rheumatoid-like polyarthritis; hydrops fetalis; chronic or recurrent bone marrow suppression in immunocompromised individuals; pancytopenia or isolated anemia, thrombocytopenia, and leukopenia; and, less commonly, hepatitis, fulminant liver failure, peripheral neuropathy, encephalopathy, and myocarditis or cardiomyopathy. The putative receptor is the glycosphingolipid globoside, which has a proud tissue distribution. Histological changes are not considered diagnostic. Electron microscopy may show B19 in lesional endothelial cells. Catastrophic skin vascular endothelial cell injury has been described in B19 infection in which in situ reverse transcription and hybridization showed B19 RNA transcripts. Vesiculopustular lesions show ballooning degeneration of keratinocytes with a mixed inflammatory cell infiltrate that may contain numerous eosinophils. Local edema, dilated vessels, and erythrocyte extravasation suggest local capillary leak. A lymphohistiocytic infiltrate with markedly abnormal atypical cells showing enlarged, hyperchromic nuclei may be present.