# Isolated osseous Rosai-Dorfman disease: a case report and review of literature

## TL;DR

A rare case of isolated bone disease resembling aggressive cancer is reported and identified as Rosai-Dorfman disease.

## Contribution

A case of primary osseous Rosai-Dorfman disease without lymphadenopathy is documented and reviewed.

## Key findings

- Isolated osseous Rosai-Dorfman disease can present as a nonspecific pelvic mass.
- Multidisciplinary investigation is crucial for accurate diagnosis.
- Primary bone RDD is rare and can mimic aggressive conditions.

## Abstract

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare histiocytic disorder characterized by proliferation of non-Langerhans cell phagocytic histiocytes. Most patients present with painless massive cervical lymphadenopathy with associated night sweats, malaise, and fever. Osseous manifestations of RDD are uncommon and primary RDD of the bone without lymphadenopathy is thought to be even rarer. It is important to maintain this entity on a differential as it can mimic an aggressive entity. This is exemplified in our case report of a 24-year-old female patient with an incidental finding of a nonspecific mass in the right hemipelvis which was determined to be isolated osseous Rosai-Dorfman disease after a multidisciplinary investigation.