Malignant lymphomas of the paranasal sinuses, which have a minimal tendency for invasion but considerable necrosis, may be misdiagnosed as an inflammatory disease, based on MRI and clinical findings. In cases where a thorough physical examination does not rule out a malignant lymphoma, an endoscopic biopsy should be immediately considered.

Gardner syndrome (GS) with odontogenic sinusitis is rare but should be suspected in patients with multiple osteomas of the skull and facial bones, excess teeth, impacted teeth, and odontomas. Early diagnosis of GS and treatment for familial adenomatous polyposis may improve prognosis.