Background: Inflammatory pseudotumor (IPT) is a benign idiopathic inflammatory condition. Clinically, it manifests as either a slow-growing tumor with little mass effect or progressively destructive mass that resembles malignancy. Here, we present a case of nasopharyngeal inflammatory pseudotumor mimicking nasopharyngeal malignancy.

Case presentation: A 70-year-old male patient complained of mild right otalgia with decreased hearing; there were no other otological symptoms or cranial nerve neuropathy. Computed tomography (CT) revealed a suspicious soft tissue density in the right fossa of Rosenmüller (pharyngeal recess), while magnetic resonance imaging (MRI) identified a diffuse and homogeneous lesion in the right fossa of Rosenmüller where T1 and T2 images were enhanced and hypointense, respectively. The patient underwent multiple right endonasal endoscopies for nasopharyngeal biopsy under general anesthesia, which showed benign nasopharyngeal tissue with chronic inflammatory cells and seromucous salivary inflammatory glands, without evidence of carcinoma or lymphoma. Consequently, he was administered corticosteroid therapy with good tolerability and response. There was no clinical or radiological evidence of recurrence after a 1-year follow-up.

Conclusion: Diagnosis of IPT is a challenge due to its malignancy-like characteristics. IPT involving the nasopharynx has characteristic MRI findings, which, together with clinical and laboratory presentations, help differentiate IPTs from malignant tumors, especially nasopharyngeal carcinoma. However, to confirm the diagnosis, a tissue biopsy is essential. Treatment of IPT of the skull base is controversial and may involve corticosteroids, radiation therapy, surgical excision, or multimodality depending on pathological subtype, ease and safety of resection, the safety of high-dose corticosteroid use, the surgeon's comfort, and the patient's preference. Other chemotherapeutic agents with or without radiotherapy may be considered in steroid-resistant patients.