Extranodal Rosai-Dorfman disease masquerading as intrathoracic invasive malignancy with ankylosing spondylitis: a case report.

INTRODUCTION: Rosai-Dorfman Disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is an uncommon histiocytic disorder. It may be associated with autoimmune diseases, but there are few reports of concurrent ankylosing spondylitis. RDD is typically characterized by massive bilateral and painless cervical lymphadenopathy, which can also involve extranodal sites and constitutional symptoms, but rarely affect the chest cavity.

CASE PRESENTATION: In this report, we present a case of a patient with a suspicious invasive anterior mediastinal lesion affecting multiple blood vessels and adjacent tissues. The patient has a history of ankylosing spondylitis. Despite extensive radiological and interventional examinations, the possibility of malignancy could not be completely ruled out. Following surgical resection of the tumor, the final pathology diagnosis suggested RDD.

CONCLUSION: Our report emphasizes the importance of considering RDD in the differential diagnosis of invasive thoracic malignancies. Thoracoscopy or mediastinoscopy biopsy can improve diagnostic accuracy. Our study contributes to an improved understanding among clinicians regarding the diagnosis and treatment of intrathoracic RDD and provides relevant evidence for future exploration of potential associations between RDD and ankylosing spondylitis.