Extraordinary Case ReportImmunohistochemical Demonstration of Parvovirus B19 Viral Protein 2 in Periflexural Exanthema in an Adult, Supporting Antibody-Dependent Enhancement as Means of Endothelial Uptake of the VirusSantonja, Carlos MD*; Pielasinski, Úrsula MD†; Polo, Jorge MD‡; Kutzner, Heinz MD§; Requena, Luis MD†Author Information Departments of *Pathology, †Dermatology, and ‡Internal Medicine, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain; and §Dermatopathologie Friedrichshafen, Friedrichshafen, Germany. Reprints: Carlos Santonja, MD, Anatomía Patológica, Fundación Jiménez Díaz, Avenida de los Reyes Católicos 2, 28040 Madrid, Spain (e-mail: [email protected]). The authors declare no conflicts of interest. The American Journal of Dermatopathology: February 2018 - Volume 40 - Issue 2 - p e19-e24 doi: 10.1097/DAD.0000000000000946 Buy Metrics Abstract Human parvovirus B19 (B19V) causes a number of skin exanthemas and has been related to both cutaneous and systemic diseases. Tropism of the virus for the rapidly proliferating erythroid progenitor cells in the bone marrow and fetal liver explains the pathogenesis of anemia and fetal hydrops. The cutaneous lesions of erythema infectiosum and other B19V-related exanthemas have been attributed to the deposition of immune complexes in the skin. We report on the immunohistochemical detection of B19V protein in the cytoplasm of dermal endothelial cells in a case of periflexural exanthema in a 28-year-old woman. An antibody-dependent enhancement mechanism of entry has been suggested for B19V in myocardial endothelial cells and could also be involved in B19V-related exanthemas. Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.