# Reactive Plasmacytosis Immediately After Immunosuppressive Therapy With Anti-human Thymocyte Immunoglobulin for Severe Aplastic Anemia: A Report of a Rare Case

## TL;DR

A rare case of reactive plasmacytosis occurred during immunosuppressive therapy for severe aplastic anemia and was linked to successful recovery.

## Contribution

This is the first reported case of reactive plasmacytosis during immunosuppressive therapy for aplastic anemia.

## Key findings

- Reactive plasma cells appeared in peripheral blood during treatment and disappeared spontaneously.
- The patient showed good hematopoietic recovery following the reactive plasmacytosis.
- Reactive plasmacytosis may indicate a positive response to immunosuppressive therapy in aplastic anemia.

## Abstract

Aplastic anemia is a hematopoietic deficiency disorder with pancytopenia, and immunosuppressive therapy is effective. We report a case in which plasma cells appeared in the peripheral blood during immunosuppressive therapy for aplastic anemia. Based on the results of morphology and flow cytometry, the plasma cells were considered reactive and disappeared spontaneously after follow-up. Thereafter, the patient had a good hematopoietic recovery. Reactive plasmacytosis has been reported in infectious and autoimmune diseases, but this is the first report of reactive plasmacytosis during immunosuppressive therapy for aplastic anemia, to our knowledge. In this case, reactive plasmacytosis was a sign preceding good hematopoietic recovery.