Nonspecific Inflammatory Tumors of the Skull Base: Case Series

Introduction: The differential diagnosis of lesions involving the skull base is extensive, and ruling out malignant neoplasms is an important goal. Inflammatory tumors of the skull base can present with multiple cranial nerve palsies and mimic malignant neoplasms. Both the diagnosis and management of lesions mimicking malignancies are challenging. We present three cases of nonspecific inflammatory tumors of the skull base.

Methods: Case series presentation and literature review.

Results: Case 1 is a 66-year-old woman who presented with mild headaches and a pressure sensation around the left eye and ear for 9 months, and left eye vision changes over a 2-month period. Her past medical history was significant for a left CPA meningioma that was previously resected through a retrosigmoid craniotomy and followed over several years with serial neuroimaging for recurrence. At the onset of her most current presentation, an MRI brain scan revealed a new extensive enhancing lesion extending from the infratemporal fossa through the foramen ovale extending into the cavernous sinus. Soft tissue core needle biopsies of the extracranial portion of the lesion and later biopsies obtained via an endoscopic endonasal approach (EEA) only showed atypical B cell infiltrate without malignancy. Cultures were negative and PCR analysis only showed 5% monoclonality, ruling out lymphoma. The patient was treated with Rituxan, and her symptoms subsequently improved with time.

Case 2 is a 37-year-old woman pathologist who presented with 12 months of diplopia, dysarthria, headaches, and mild right facial paresthesia. An MRI scan showed an enhancing lesion of the cranial middle fossa with extension into the prepontine cistern. Biopsies obtained through an EEA revealed only an acute and chronic inflammatory process with negative cultures. She was treated with steroids and close serial imaging. Her symptoms improved over the intervening 1 month, and the skull base lesion volume decreased.

Case 3 is a 76-year-old woman that presented with bilateral hearing loss, left facial droop, and nonspecific headaches over 5 months. She was found to have an enhancing lesion extending from the left jugular foramen through the infratemporal fossa to the cranial middle fossa. Biopsy samples obtained through an EEA revealed only chronic inflammation without evidence of malignancy. She was treated with prednisone and, despite a stable appearance on serial neuroimaging studies, her symptoms have worsened. She is being evaluated for radiation therapy.

Conclusion: The cases presented were diagnosed as nonspecific inflammatory lesions without evidence of malignancy. The diagnosis of inflammatory pseudotumor could not be made in these cases because the pathognomonic spindle cells without nuclear atypia admixed among the inflammatory infiltrate could not be identified on histology. There are little data available about effective treatment. Biopsy is important to rule out malignancy. These cases typically respond to steroid therapy, but as Case 3 demonstrates the steroids are not always effective. This case is being evaluated for radiation therapy. Benign inflammatory lesions should be considered in the light of nonspecific histology.