# Unicentric Castleman disease treated with rituximab before surgery: clinicopathologic findings

## TL;DR

This paper reports a case of unicentric Castleman disease partially responding to anti-CD20 therapy before surgery, highlighting changes in the tumor and treatment response.

## Contribution

The study provides new insights into the histological effects of anti-CD20 therapy in unicentric Castleman disease.

## Key findings

- The patient showed only a partial response to anti-CD20 therapy before surgery.
- Histological changes in the surgical specimen were observed following the treatment.
- The local microenvironment may influence the efficacy of anti-CD20 therapy.

## Abstract

Castleman disease (CD) is a rare lymphoproliferative disorder with unique clinicopathological features, including two distinct clinical subtypes categorized as unicentric (UCD) and multicentric (MCD). UCD usually involves a single lymph node site presenting with no or minimal local symptoms. Histologically, most UCD cases exhibit regressive hyaline vascular germinal centers, characterized by penetrating vessels, dendritic hyperplasia/dysplasia, and increased interfollicular vascularity. While complete surgical excision is the standard treatment for UCD, cases treated with neoadjuvant anti-CD20 therapy have been reported. Here, we describe a UCD case treated with anti-CD20, that showed only a partial response. We detail the clinical findings and the histological changes observed in the surgical specimen following therapy, and discuss the potential influence of the local microenvironment on the therapeutic efficacy of anti-CD20.

The online version contains supplementary material available at 10.1007/s00277-025-06527-3.