The most important step in the differential diagnosis of mass lesions of the central skull base is to rule out malignant neoplasms. However, nonneoplastic lesions, such as infections or nonspecific inflammatory lesions of the skull base, can mimic malignant processes. In this study, the authors analyzed seven cases of nonneoplastic noninfectious mass-forming lesions involving the central skull base. In most cases, malignant processes were suspected at the initial phase of diagnostic work-up, but subsequent histologic examinations revealed that these lesions consisted of inflammatory cells and fibrosis without neoplastic cells. Common manifestations were pain and other neurological symptoms related to the involved anatomical sites. A variety of neurological dysfunctions of the cranial nerves not including the olfactory and spinal accessory nerves were observed. No patient developed separate lesions outside the head and neck region. After the pathologic diagnosis, most of the patients were treated with oral steroid therapy, with initial doses of prednisolone, 60 to 100 mg/d. It was difficult to relate responsiveness to steroid therapy with the histologic degree of sclerosis, fibrosis, or chronicity of the disease in these cases. Otolaryngologists should be aware of this disease when making treatment decisions for their patients with skull base lesions.