Whole-body diffusion-weighted MRI in a case of Rosai-Dorfman disease with exclusive multifocal skeletal involvement.

Rosai-Dorfman disease (RDD) is a rare disorder and usually presents with painless bilateral cervical lymphadenopathy. About 43% of RDD patients show extranodal involvement, including bones (8%). As RDD is a systemic disease, which can involve lymph nodes, bones, skin, kidneys, respiratory tract, parotid gland, orbital cavity and the central nervous system, whole-body imaging may be useful for the assessment of extent, distribution and follow-up of disease. Whole-body diffusion-weighted MRI is able to demonstrate lesions and to assess therapy response without the need for radiation or intravenous contrast agent. Here, we report a case of a 15-year-old boy with primary skeletal RDD without lymphadenopathy, who was staged and followed by whole-body diffusion-weighted MRI.