Nasal NK/T-cell lymphoma: computed tomography and magnetic resonance imaging findings.

BACKGROUND Primary nasal natural killer (NK)/T-cell lymphoma is the most common cellular subtype seen in nasal lymphomas. It is rare in the Western population but occurs more frequently in Asia, South America, and Mexico. The purpose of this study was to describe the computed tomography (CT) and magnetic resonance (MR) imaging findings of primary nasal NK/T-cell lymphoma. METHODS During the period between January 1990 and June 2006, the CT (n=24) and MR (n=6) images of 24 patients with biopsy-proved nasal NK/T-cell lymphoma were reviewed retrospectively. Both CT and MR images were evaluated for site and extent of disease and for pattern of involvement of adjacent areas. RESULTS The most common symptoms at presentation were nasal obstruction, nasal discharge, and epistaxis. There was involvement of the unilateral nasal cavity in 16, bilateral nasal cavity including nasal septum in 5 and nasal choana in 3. Sites of extension outside the nasal cavity included tumor extension into paranasal sinuses (n=15), nasopharynx (n=5), nasal labial fold (n=3), oropharynx (n=2), infratemporal fossa (n=2), other subcutaneous soft tissue of the face (n=2) and anterior cranial fossa base (n=1). Bony destruction was demonstrated in 18 cases, involving the sinus bony wall (n=15), nasal turbinate (n=10), lamina papyracea (n=6), orbital floor (n=3), and hard palate (n=2). Regional lymphadenopathy was also detected in 3 patients with nasal NK/T-cell lymphoma. CONCLUSION The CT and MR appearances of nasal NK/T-cell lymphoma are nonspecific, and the diagnosis requires histologic confirmation. However, the differential diagnosis of nasal NK/T-cell lymphoma should be included if the images present soft tissue of the nasal cavity with bony erosion or destruction; involvement of the orbital cavity, nasopharynx and infratemporal fossa; and subcutaneous or nasolabial fold soft tissue infiltration, especially in Asian populations.