An autopsy case of acute myocarditis with unique lymph node findings characterized by the proliferation of reactive plasmablasts

• Published in: Journal of Clinical and Experimental Hematopathology Vol. 60; no. 3; pp. 108 - 112
• Main Authors: Ohtani, Haruo, Nozaki, Yoshihiro, Murakami, Takashi, Lin, Lisheng, Shiono, Junko, Miyazawa, Masaaki
• Format: Journal Article
• Language: English
• Published: Japan The Japanese Society for Lymphoreticular Tissue Research 01-01-2020; JSLRT
• Subjects: Acute Disease; Adolescent; Antigens, CD - analysis; Autopsy; Case Report; Cell Proliferation; double-labeling immunohistochemistry; Humans; Lymph Nodes - cytology; Lymph Nodes - pathology; Male; Myocarditis - pathology; Plasma Cells - cytology; Plasma Cells - pathology; plasmablasts; reactive lymphadenopathy; double-labeling immunohistochemistry; plasmablasts; reactive lymphadenopathy
• ISSN: 1346-4280; 1880-9952
• DOI: 10.3960/jslrt.20023

We report an autopsy case of acute myocarditis, in which the mediastinal lymph nodes exhibited unique findings. A 15-year-old Japanese boy was diagnosed with the secondary onset of acute myocarditis. No viruses were identified. Autopsy confirmed acute lymphocytic myocarditis. Lymphadenopathy was observed, especially in pulmonary hilar/mediastinal areas. Microscopically, interfollicular areas were uniformly filled with medium-sized, round cells that resembled lymphocytes. They were immunohistochemically CD3- CD5- CD19+ CD20- CD79a- Pax-5- CD138+ MUM1+ LMP1- EBNA2- cytoplasmic IgG+ IgA- and IgM-. No monotypia was observed for kappa and lambda light chains, and multiplex polymerase chain reaction analyses of immunoglobulin heavy chain variable region diversity demonstrated oligoclonal peaks, suggesting reactive change. IgG+ or VS38c+ cells frequently co-expressed Ki-67 (up to 80%). We considered these cells abundantly present in lymph nodes to be reactive plasmablasts because they were early plasma cells with proliferative activity.