The initial biopsy specimen, obtained on the 10th day of disease, demonstrated leukocytoclastic vasculitis. Microscopic examination of the second biopsy specimen showed a moderate perivascular infiltrate of histiocytes with relatively plentiful cytoplasm, a few multinucleated histiocytes, some neutrophils, and rare eosinophils. The histiocytic cells stained with antibodies against factor XIIla antigen and showed negative staining for CDla antigen and S100 protein.
The patient's skin lesions regressed spontaneously within 1 month after his visit, leaving a slight atrophy in some areas.
Multiple Erythematous Plaques on a Child—Diagnosis. Arch Dermatol. 2003;139(4):531-536. doi:10.1001/archderm.139.4.531-a