A 59-year-old woman presented with arthralgia of the left knee. Magnetic resonance imaging showed high-intensity lesions on short tau inversion recovery sequences in both the tibia and femur (Picture 1). Bone scintigraphy showed the accumulation in multiple joints (Picture 2). A left femoral bone biopsy demonstrated chronic osteomyelitis. SAPHO syndrome and chronic recurrent multifocal osteomyelitis were listed as differential diagnoses. Six months later, the patient presented with a nasal mass and cervical lymphadenopathy. A lymph node biopsy was performed, and the pathology showed histiocytosis and emperipolesis, which involves the non-destructive phagocytosis of lymphocytes and erythrocytes, and was immunohistochemically positive for S100 (Picture 3a, b). Based on these findings, she was diagnosed with Rosai-Dorfman disease (RDD). A review of the bone biopsy specimen additionally revealed positivity for emperipolesis and S100, findings consistent with RDD. RDD is a rare non-neoplastic histiocytotic disease (1). Bone lesions in RDD occur in approximately 10% of cases, commonly in the cranium, facial bones, or tibia (2).
Picture.
The authors state that they have no Conflict of Interest (COI).
References
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