Abstract: Sinus histiocytosis with massive lymphadenopathy, also known eponymously as Rosai-Dorfman disease, is a rare disease that is defined as a self-limiting proliferation of non-Langerhans histiocytes. The most common and typical presentation is painless bilateral cervical lymphadenopathy. Bone involvement in Rosai-Dorfman disease occurs in fewer than 10% of patients. In osseous Rosai-Dorfman disease, most patients suffer from a chronic course, and the cranial and facial bones as well as tibia are the most common sites. The clinical manifestations of the disease lack specificity, and the diagnosis is mainly based on routine pathological and immunohistochemical staining. Clinical presentation involves pain and swelling. On radiograph, typically, skeletal lesions are lytic and intramedullary, sometimes with surrounding sclerosis. The etiology of Rosai-Dorfman disease has been poorly understood so far. It has been hypothesized that Rosai-Dorfman disease may involve underlying host immune dysregulation, IgG4- related disease, various autoimmune disorders and gene mutation. Treatments primarily depend on specific locations of Rosai- Dorfman disease, including curettage or resection, steroids and chemotherapy. Since the clinical and radiologic manifestations of Rosai-Dorfman disease are often suggestive of malignancy, these patients might receive aggressive therapy. Whole-body PET/CT has proven to be a useful method for the management of Rosai-Dorfman disease, primarily for the staging, follow-up and evaluation of treatment results.

Key words: Bone disease, Rosai-Dorfman disease, Sinus histiocytosis, Diagnosis, Therapy