Intradural eosinophilic granuloma with intraparenchymal invasion: a new growth pattern.

Background: Eosinophilic granuloma is a form of Langerhans' cell histiocytosis, most commonly involving the skeletal system. We present the first case of an eosinophilic granuloma originating from the dura mater with secondary parenchymal and osseous invasion.

Case report: A 32-year-old man was referred to us for headache and swelling in the right parietal region and a history of minor head trauma. The radiological and surgical findings were suggestive of meningosarcoma. Intraoperatively the lesion was found to originate from the dura mater. Histological diagnosis was eosinophilic granuloma. After a 21-month follow-up period, MRI was negative.

Conclusion: Intradural development is a possible growth pattern of eosinophilic granuloma. An inflammatory process of the dural membrane with migration of Langerhans' cells could be the physiopathological basis for the formation of intradural eosinophilic granuloma. This is a mechanism similar to that of chronic subdural haematoma formation. Histological demonstration of eosinophilic granuloma cells around the lesion margin suggests the need to remove dura mater peripherally to the lesion.