A case of hypertrophic cranial pachymeningitis developed skull lesion

We report a case of hypertrophic cranial pachymeningitis (HCP) developed skull lesion. A 70-year-old male presented with the symptom of left hemiconvulsion. MRI revealed that the enhanced intraosseous mass infiltrated into the the dura and brain parenchyma under the parasagittal region of the right parietal bone. Histological examination revealed chronic inflammation with lymphoplasmacytic infiltrate and fibrosis of both intraosseous mass and dural invasive lesion. Steroid therapy resulted in improvement of clinical symptoms and enhanced lesion of MRI. Three years later, the patient presented with generalized convulsion and weakness of right upper and lower limbs. MRI revealed dural thickening with gadolinium enhancement in the bilateral parasagittal region and falx. Angiography showed occlusion of the superior sagittal sinus. The cause of relapsing symptoms in this patient may have been related to the occlusion of the superior sagittal sinus, due to HCP. We considered that the incipient intraosseous mass resulted from a response of the marrow by destructive progression of chronic inflammation passed through the fracture crack or the cavity of arachnoid granulation.