Inflammatory pseudotumor of the nasopharynx and skull base is a benign, idiopathic disease that is often mistaken for a neoplasm or infection owing to its aggressive behavior and clinical presentation. It can present as a progressively destructive mass and should be considered when repeated tissue biopsies reveal acute or chronic inflammation without evidence of malignant disease or infection. We present 4 cases of nasopharyngeal inflammatory pseudotumor with skull base invasion occurring in patients with diabetes mellitus (DM). These patients had repeated negative results from biopsies and cultures, and none had associated cervical lymphadenopathy despite having an aggressive destructive mass. We suggest that these findings, coupled with clinical suspicion, will be helpful in making the correct diagnosis of inflammatory pseudotumor. This is critical in the management of these patients to institute the correct treatment plan.