Sinonasal lymphoma is a rare hematologic malignancy involving the paranasal sinuses and nasal cavity. The most common subtype is extranodal NK/T-cell lymphoma, which has a strong association with Epstein-Barr virus (EBV) and is particularly prevalent in East Asian and Latin American populations. Diffuse large B-cell lymphoma (DLBCL) is the second most frequent subtype. Sinonasal lymphoma accounts for approximately 5-8% of all sinonasal malignancies and can be distinguished from other sinonasal tumors by its characteristic imaging features. Characteristically, lymphoma demonstrates submucosal soft tissue infiltration rather than bone destruction; this feature is an important distinguishing criterion from epithelial tumors such as squamous cell carcinoma. NK/T-cell lymphoma is also known as 'lethal midline granuloma' and produces midline necrotizing destructive lesions. The disease can be locally aggressive and may extend to the orbit, palatal region, nasopharynx, and intracranial structures.
Age Range
40-75
Peak Age
60
Gender
Equal
Prevalence
Rare
Sinonasal lymphoma develops through infiltrative accumulation of lymphoid cells in submucosal and perineural spaces. In NK/T-cell lymphoma, EBV-infected NK or T cells undergo clonal proliferation in the nasal mucosa and exhibit an angioinvasive growth pattern causing vascular damage and coagulative necrosis — this necrosis manifests on imaging as heterogeneous enhancement and necrotic areas. Because tumor cells spread in the submucosal plane, bone destruction is typically late and minimal; this explains the preserved appearance of bones on CT. Ischemic necrosis resulting from angioinvasion causes diffusion restriction on DWI because necrotic tissue loses cell membrane integrity and intracellular water is released. Homogeneous soft tissue enhancement reflects the dense cellularity and relative preservation of vascular architecture; however, as angioinvasion progresses, necrotic areas become prominent and heterogeneous enhancement emerges.
The most characteristic feature of sinonasal lymphoma is preservation of surrounding bony structures even in large-sized masses. The nasal septum, lateral nasal wall, lamina papyracea, and sphenoid bone are typically intact. This finding reflects lymphoma's submucosal infiltrative growth pattern and is a pathognomonic distinguishing feature from epithelial carcinomas showing aggressive bone destruction. In NK/T-cell lymphoma, bone destruction may develop in advanced stages, but this is usually a consequence of angioinvasive necrosis rather than primary tumor invasion.
A homogeneous soft tissue density mass is observed in the nasal cavity and/or paranasal sinuses. Lymphoma is typically isodense to muscle (40-50 HU) and does not contain significant calcification. The mass is usually midline in location and may grow to fill the bilateral nasal cavity. Bony structures are mostly preserved or show only minimal remodeling — this feature is a distinguishing finding from carcinomas that demonstrate aggressive bone destruction. Heterogeneous areas may be seen in NK/T-cell type due to midline necrosis.
Report Sentence
A midline homogeneous soft tissue density mass is observed in the nasal cavity without significant destruction of surrounding bony structures; these findings are primarily consistent with lymphoma.
On contrast-enhanced CT, the lymphoma mass demonstrates homogeneous and moderate enhancement. Enhancement is typically diffuse and uniform, indicating a solid mass. In advanced NK/T-cell lymphoma, enhancement may become heterogeneous due to necrosis resulting from angioinvasion, and central hypodense areas may be observed. Peritumoral mucosal thickening and obstructive sinusitis findings may accompany. Evaluation of retropharyngeal and cervical lymph nodes is critical for staging.
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The mass demonstrates homogeneous moderate enhancement on contrast-enhanced examination without central necrotic areas; this enhancement pattern is consistent with lymphoproliferative disease.
On T2-weighted images, the lymphoma mass demonstrates intermediate-to-low signal intensity — this finding reflects high cellularity and is distinctly different from benign lesions such as polyps, retention cysts, or mucoceles that typically appear hyperintense on T2. Signal intensity is isointense or mildly hyperintense compared to muscle. In NK/T-cell lymphoma, necrotic areas may be seen as focal hyperintense foci on T2. Peritumoral edema or obstructive sinusitis may produce T2 hyperintense fluid in surrounding sinuses. This T2 signal characteristic is specific to the dense cellular architecture of lymphoma and is lower than most other sinonasal tumors.
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A mass with intermediate-to-low signal intensity on T2-weighted sequence is observed in the nasal cavity; this signal characteristic suggests high cellularity and should be evaluated for lymphoproliferative disease.
On DWI, the lymphoma mass demonstrates marked diffusion restriction — bright signal on high b-values (b=1000) and low signal on ADC maps. ADC values are typically in the range of 0.5-0.8 × 10⁻³ mm²/s, which is significantly lower than most sinonasal tumors. Diffusion restriction is the strongest MR indicator of lymphoma's dense cellular structure and increases diagnostic confidence. In NK/T-cell lymphoma, diffusion restriction may be lost in necrotic areas with focally elevated ADC values. DWI also plays a critical role in assessing treatment response — an increase in ADC values is expected after successful treatment.
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The mass demonstrates marked diffusion restriction on DWI (ADC: ~0.6 × 10⁻³ mm²/s); this finding strongly suggests high cellularity and lymphoproliferative disease.
On T1-weighted images, the lymphoma mass shows isointense or mildly hypointense signal compared to muscle. T1 signal is homogeneous, and this feature helps differentiate from tumors with high fat content (such as liposarcoma) or hemorrhagic lesions (T1 hyperintense). On post-contrast T1 fat-sat sequences, diffuse and homogeneous enhancement is observed — this enhancement pattern reflects lymphoma's homogeneous cellular structure and vascular distribution. If perineural spread is present, linear enhancement along affected nerves may be observed — particularly along the infraorbital nerve and vidian canal.
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The mass shows isointense signal to muscle on T1-weighted images with homogeneous diffuse enhancement on post-contrast sequences.
Sinonasal lymphoma demonstrates intense FDG uptake on FDG PET-CT, with SUVmax values typically ranging from 10-25. FDG uptake is usually most intense in the DLBCL subtype (SUVmax >15). NK/T-cell lymphoma also shows high FDG uptake, but focal decrease may be seen in necrotic areas. PET-CT is superior to CT and MRI in evaluating local disease extent, distant involvement, and staging. The Deauville scoring system is used for treatment response assessment (interim and end-of-treatment PET). False positive risk is low in sinonasal lymphoma, but granulomatous diseases (GPA/Wegener) and active infection can cause false positive results.
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Intense FDG uptake is observed in the nasal cavity mass (SUVmax: __); this finding suggests high metabolic activity and lymphoproliferative disease.
The most important finding specific to lymphoma on bone window CT is preservation of bony structures despite the size of the mass. The nasal septum, lateral nasal wall, lamina papyracea, and sphenoid bone are usually intact or show only mild remodeling — this is distinctly different from the aggressive bone destruction of squamous cell carcinoma and adenoid cystic carcinoma. However, in advanced stages or NK/T-cell lymphoma, bone destruction may develop due to angioinvasive necrosis — in this case, hard palate perforation, nasal septum perforation, or orbital wall erosion may be observed. The bone preservation phenomenon is explained by lymphoma's submucosal infiltrative growth pattern.
Report Sentence
Despite the size of the nasal cavity mass, surrounding bony structures (nasal septum, lateral nasal wall, lamina papyracea) are preserved without significant destruction; this finding is considered pathognomonic for lymphoma.
Ultrasonography has a limited role in sinonasal lymphoma but can be used for superficially located lesions (hard palate, alveolar ridge, gingiva) or cervical lymph node assessment. Lymphomatous tissue typically appears as a homogeneous hypoechoic solid mass — internal echo architecture is uniform and low in intensity. On power Doppler, increased vascularity and low resistance index (RI <0.6) may be observed in the lymphomatous mass. In cervical lymph nodes, round morphology, loss of hilum, and homogeneous hypoechoic appearance suggest lymphoma. Ultrasound-guided fine needle aspiration or core biopsy can be performed.
Report Sentence
A homogeneous hypoechoic solid mass is observed in the evaluated region with increased vascularity and low resistance index on power Doppler; lymphoproliferative disease should be primarily considered.
Criteria
EBV-positive NK or T cell proliferation, midline location, angioinvasive growth pattern. CD56+, CD2+, cytoplasmic CD3ε+. Most common sinonasal lymphoma subtype in East Asia and Latin America. Aggressive clinical course, relative resistance to chemotherapy, sensitivity to radiotherapy.
Distinct Features
Midline necrotizing destruction (lethal midline granuloma), septal perforation, palatal erosion, intense angioinvasion, heterogeneous enhancement (necrosis areas), bone preservation in early stage but necrotic bone destruction in advanced stage on CT, marked restriction on DWI. Risk of hemophagocytic syndrome complication.
Criteria
Large B cell proliferation, CD20+, CD79a+, BCL-6 and/or BCL-2 expression. Most common sinonasal lymphoma subtype in Western countries. Usually in older adults (60-70 years), slight male predominance. Good response to R-CHOP chemotherapy.
Distinct Features
Less midline necrosis compared to NK/T-cell type, more homogeneous enhancement, more prominent bone preservation, higher FDG uptake (SUVmax >15), larger mass size. Usually unilateral maxillary sinus or nasal cavity involvement. Very low ADC values on DWI (0.5-0.7 × 10⁻³ mm²/s).
Criteria
Low-grade B cell lymphoma, CD20+, CD79a+, CD5-, CD10-, BCL-6-. Rare but important subtype in sinonasal region. Slow growth, low aggressiveness, good prognosis. May develop on background of chronic inflammation (Hashimoto thyroiditis, Sjögren syndrome, Helicobacter pylori-associated gastritis analogy).
Distinct Features
Small, well-defined mass, homogeneous enhancement, very low aggressiveness, bone destruction usually absent, FDG uptake lower than other subtypes (SUVmax <5-8), less prominent diffusion restriction on DWI. Treatment: local radiotherapy usually sufficient.
Criteria
High-grade aggressive B cell lymphoma, c-MYC translocation (t(8;14)), CD20+, CD10+, BCL-6+, Ki-67 ~100%. Seen in children and young adults. Endemic form (Africa, EBV-associated) and sporadic form. Very rapid proliferation — tumor doubling time 24-48 hours.
Distinct Features
Rapidly growing aggressive mass, bone destruction in maxilla/mandible (unlike other lymphomas), intense FDG uptake, very low ADC on DWI (lowest among all lymphomas), heterogeneous enhancement (necrosis common), tumor lysis syndrome risk. May present with facial swelling in children.
Distinguishing Feature
SCC demonstrates aggressive bone destruction (destructive osteolysis, cortical disruption), while bone is preserved in lymphoma. Heterogeneous enhancement and necrosis are more common in SCC. SCC usually originates from a single sinus and invades adjacent structures, while lymphoma can involve multiple sinuses through submucosal spread.
Distinguishing Feature
Olfactory neuroblastoma originates from the olfactory cleft (cribriform plate) and shows cranial extension (dumbbell shape — Kadish staging). Peripheral cystic component (intracranial) and calcification may be seen. Lymphoma lacks cribriform plate origin and dumbbell morphology. Olfactory neuroblastoma shows hyperintense T2 signal while lymphoma demonstrates intermediate-to-low T2 signal.
Distinguishing Feature
GPA (Wegener) shows bilateral nasal cavity involvement, septal perforation, and bone destruction — imaging findings can mimic NK/T-cell lymphoma. However, granulomatous inflammation, c-ANCA positivity, sinusitis with lower respiratory tract involvement (pulmonary nodules/cavities), and glomerulonephritis triad are distinguishing in GPA. DWI restriction is less prominent in GPA than lymphoma.
Distinguishing Feature
Melanoma shows hyperintense T1 and hypointense T2 signal due to melanin content (paramagnetic melanin effect) — this signal pattern is distinctly different from lymphoma. Signal characteristics are not typical in amelanotic melanoma. Bone destruction is more prominent in melanoma compared to lymphoma and peritumoral hemorrhage is common.
Distinguishing Feature
Inverted papilloma shows pathognomonic 'cerebriform' enhancement pattern (convoluted pattern) — striped/lamellar alternating enhancing and non-enhancing bands. This pattern is not seen in lymphoma. Inverted papilloma is usually unilateral and originates from the lateral nasal wall. DWI restriction is not as prominent as in lymphoma.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
Treatment response PET-CT at interim (after 2-3 cycles) and end of treatment. Surveillance imaging every 3-6 months for first 2 years, then annually for 5 years.Biopsy is mandatory for sinonasal lymphoma diagnosis — imaging alone is not sufficient. In NK/T-cell lymphoma, the treatment protocol is radiotherapy-weighted (SMILE regimen: steroid, methotrexate, ifosfamide, L-asparaginase, etoposide + RT). R-CHOP chemotherapy is standard in DLBCL. PET-CT and bone marrow biopsy are required for staging. Ann Arbor staging system is used. Hemophagocytic lymphohistiocytosis (HLH) complication can be life-threatening in NK/T-cell lymphoma. EBV DNA viral load monitoring is critical for treatment monitoring.
Sinonasal lymphoma requires biopsy for diagnosis. NK/T-cell type is particularly common in Asian populations and associated with EBV. Treatment is chemotherapy combined with radiotherapy. Diffusion restriction is important in evaluating treatment response.