Co-occurrence of intracranial Rosai-Dorfman disease and Langerhans histiocytosis of the skull: case report and review of literature.

: Rosai-Dorfman Disease involves histiocytic proliferation of the lymphatic system. Extranodal disease involving the central nervous system is uncommon. Furthermore, the combination of this disease entity with Langerhans cell histiocytosis is an even rarer phenomenon that has only recently been highlighted. A young male, who had previously undergone surgical excision of a skull lesion that was reported as Langerhans histiocytosis presented with an intracranial lesion mimicking a meningioma. Histopathology of the lesion was reported as being consistent with Rosai-Dorfman disease and the patient is currently undergoing chemotherapy. This is only the second report of the co-occurrence of Langerhans histiocytosis and Rosai-Dorfman disease in the cranium and intracranial cavity. The possibility that the diseases represent different spectra of the same underlying pathology is one that merits more detailed analysis, especially at the genomic level.