Aim: To describe a rare case of nasopharyngeal inflammatory pseudotumor (IPT) with skull base invasion. Background: Inflammatory pseudotumor is a nonneoplastic lesion characterized by fibrosis and inflammation. It can be locally aggressive and resemble malignancy and extranodal lymphoma. It has been described in nearly every anatomic site throughout the body. Although rare, the involvement of the skull base is associated with more aggressive behavior. Case description: The authors present the case of a 63-year-old male with a 3-month history of right otorrhea, headache, and facial pain in the sensitive territory of the right trigeminal nerve (V3). Magnetic resonance imaging (MRI) showed an infiltrative lesion of the posterior wall of the nasopharynx with poorly defined limits, extended deep into the retropharyngeal and prevertebral space, with bone erosion of the occipital clivus and petrous apex. The patient performed three biopsies of the nasopharynx suggestive of a fibroinflammatory process. Inflammatory pseudotumor was diagnosed and the patient did a long course of high-dose systemic corticotherapy with good clinical and radiological response. Conclusion: Biopsy is essential for the diagnosis of IPT, although it usually just shows inflammatory changes. Magnetic resonance imaging features of this entity are ill-defined lesions with local infiltration, hypointensity on T2-weighted sequences, and weak contrast enhancement, usually with an absence of cervical lymphadenopathies. The treatment of IPT involving the skull base has been controversial but can include corticotherapy and radiotherapy. Clinical significance: This case report highlights the relevance of including IPT in the differential diagnosis of infiltrative nasopharyngeal and skull base lesions, especially when biopsies and cultures are negative.