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Sinonasal lymphoma

Sinonasal lymphoma presents with variable nonspecific symptoms including nasal obstruction, rhinorrhea, epistaxis, and facial swelling; may present with visual or neurological symptoms from orbital or intracranial extension. Most commonly diagnosed in patients aged 50-70 years (DLBCL) or 40-60 years (ENKTL).

Key Images

Image

Look For First
  • Diffusely infiltrating soft-tissue lesion extending along walls of paranasal sinuses and nasal cavity
  • Discrete mass-like lesion in maxillary sinus (DLBCL) or nasal cavity (ENKTL)
  • Restricted diffusion on DWI with low ADC values indicating high cellularity
Key Image Findings
  • CT shows soft tissue attenuation iso- to hyperattenuating regions relative to muscle, reflecting high nucleocytoplasmic ratio of lymphoid cells.
  • MRI T1 demonstrates intermediate signal intensity without specific fat saturation artifacts.
  • MRI T2 shows variable signal, typically somewhat hypointense compared to cerebrospinal fluid, reflecting dense cellularity.
  • Post-gadolinium T1 enhancement is variable and usually homogeneous, lacking the heterogeneous enhancement seen in squamous cell carcinoma.
  • DWI shows diffusion restriction with correspondingly low ADC values, a key feature reflecting cellularity and architectural disarray.
  • Lesions may present as diffusely infiltrating disease extending along sinonasal walls or as discrete mass; DLBCL favors maxillary sinus and nasal cavity, while ENKTL preferentially involves nasal cavity.
  • CT is superior for detecting associated bone destruction, which helps stage the disease and assess surgical feasibility.
  • MRI provides optimal assessment of locoregional extent including orbital invasion, intracranial extension, and skull base involvement.
Differential Diagnosis
  • Sinonasal squamous cell carcinoma: typically shows heterogeneous enhancement and keratinization; lacks the homogeneous enhancement pattern of lymphoma.
  • Sinonasal granulomatosis with polyangiitis (GPA): may show similar infiltrative pattern but usually has associated systemic vasculitis and necrotizing inflammation on pathology.
  • Adenoid cystic carcinoma: shows characteristic perineural spread and typically more infiltrative margins; different enhancement pattern.
  • Sinonasal undifferentiated carcinoma: presents as aggressive mass with greater bone destruction; lacks homogeneous enhancement of lymphoma.
  • Olfactory neuroblastoma: typically midline in nasal cavity with superior extension through cribriform plate; shows different imaging characteristics.
  • Sinonasal mucosal melanoma: may show T1 hyperintensity from melanin; demonstrates heterogeneous enhancement pattern.
Discussion

Sinonasal lymphomas are almost always non-Hodgkin lymphomas and may be primary (disease isolated to sinonasal region) or secondary (systemic disease); most sinonasal presentations are part of systemic disease.

DLBCL predominates in Western populations (~80%) and favors maxillary sinus; ENKTL occurs more frequently in Asian and Central/South American populations and typically arises in nasal cavity.

Unlike most other sinonasal malignancies, sinonasal lymphoma is treated primarily with combined chemoradiotherapy rather than surgical resection, making accurate diagnosis critical for treatment planning.

DLBCL has a significantly better 5-year survival rate (70%) compared to ENKTL (50%), influencing prognostic discussions with patients.

Nasal cavity tumors present earlier due to anatomic access and symptoms, while paranasal sinus tumors may achieve larger size before symptoms develop.

The homogeneous enhancement pattern and restricted diffusion help distinguish lymphoma from other sinonasal malignancies, which typically show heterogeneous enhancement.

Reporting Pearls

Report sinonasal lymphoma by describing it as a "homogeneously enhancing sinonasal soft-tissue lesion with restricted diffusion (low ADC), either as a discrete mass or diffusely infiltrating the paranasal sinuses and nasal cavity," and specify the site of origin and extent of locoregional disease including any orbital, intracranial, or skull base involvement to guide chemoradiotherapy planning.

Pitfalls
  • Confusing lymphoma with squamous cell carcinoma, which typically shows heterogeneous rather than homogeneous enhancement and more aggressive bone destruction.
  • Misdiagnosing inflammatory or infectious sinonasal disease (sinusitis, granulomatosis) as lymphoma based on imaging alone; diagnosis requires tissue confirmation.
  • Underestimating locoregional extent on CT alone; MRI is essential for detecting orbital invasion and intracranial extension that affects treatment planning.
  • Failing to perform staging imaging of the chest and abdomen, as apparent primary sinonasal lymphoma is often secondary to systemic disease, which affects prognosis and treatment.
Source: Reference source

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