Spontaneous regression of an anterior skull base mass.

Spontaneous regression of an intracranial mass is rare. We report a 77-year-old man with spontaneous regression of an anterior skull base mass suspected to be an inflammatory pseudotumor. The patient attended our outpatient department approximately once per month for a regular check-up following a brain stem infarction. A small mass was detected at the anterior skull base by MRI. The mass gradually grew to about 3 cm over a period of 5 years and then remained stable for 3 years. Thereafter, the mass showed spontaneous regression 8 years after it was first visible on MRI. 'Inflammatory pseudotumor' is a broad category and the natural history of these lesions is highly variable. Although the definition does include some types of malignant lesion, most masses are benign lesions that can regress spontaneously, as in our patient. A 'wait-and-see' policy is appropriate for such patients.