Idiopathic hypertrophic cranial pachymeningitis with perifocal brain edema.

Idiopathic hypertrophic cranial pachymeningitis (IHCP) consists of meningeal thickening due to chronic inflammation for which no cause such as infection, specific granulomatous disease, or malignancy is demonstrable. We present a case of IHCP with perifocal brain edema suggesting mass lesion with its magnetic resonance imaging (MRI) and pathologic findings. A 36-year-old woman was admitted to our hospital in August 2001 with a complaint of motor weakness in her left leg for 1 month. Magnetic resonance imaging with gadolinium revealed enhancement of the thickened dura mater and perifocal edema in the right frontoparietal region suggesting a mass lesion. Histological examination of the biopsy specimen revealed a dense fibrous cellular tissue. There was no obvious inflammatory infiltrate but in some areas between fibrous bundles one or two lymphocytes were detected. According to our knowledge, our patient is the second report in the literature of IHCP with focal edema causing a mass effect.