[Idiopathic hypertrophic pachymeningitis of the cavernous sinus mimicking meningioma with complete occlusion of the carotid artery].

Idiopathic hypertrophic pachymeningitis (IHPM) is a rare inflammatory entity characterized by the idiopathic thickening of the dura mater. An increasing number of cases have been reported involving the cavernoss sinus. We present the case of a patient with IHPM who was diagnosed of meningioma and showed a complete occlusion of the intracavernous carotid artery. This 42 years old woman was sent to our hospital to be treated radiosurgicaly with the diagnosis of meningioma. The diagnosis was based on MRI findings and on the temporal resistance to corticoid treatment. A complete study of the patient demonstrated the inflammatory nature of the lesion, which improved after long corticosteroid treatment. The differential diagnosis between meningioma and IHPM may be complex because of the similarities in image findings and the temporal resistance to corticosteroids shown by IHPM, thus we emphasize the usefulness of the SPECT to differentiate between inflammation and tumor in this clinical setting. In addition, our patient showed a total occlusion of the intracavernous carotid artery and, as far as we know, this is the first case with such a finding reported in the literature.