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Sinonasal malignancies

Sinonasal malignancies present with non-specific symptoms such as nasal obstruction, facial pain, headaches, rhinorrhea, and epistaxis; diagnosis is often delayed due to mimicry of benign sinonasal pathology.

Key Images

Undifferentiated carcinoma

Adenocarcinoma

Look For First
  • Bony erosion or invasion through the sinonasal walls into adjacent compartments (orbits, intracranial space, oral cavity)
  • Irregular or polypoid mass filling the nasal cavity or sinuses with variable attenuation on CT or signal on MRI
  • Enhancement characteristics and perineural spread on MRI to assess local staging and resectability
Key Image Findings
  • CT shows ovoid, polypoid, or irregular mass with variable attenuation (iso-, hyper-, or hypoattenuating relative to muscle), and specific calcifications may suggest histology: chondroid calcifications favor chondrosarcoma, melanin density suggests mucosal melanoma, and mucinous density indicates adenocarcinoma.
  • Bony erosion and invasion into adjacent regions including the orbits, intracranial compartment, facial skeleton, and base of skull are critical for surgical planning and staging.
  • MRI demonstrates variable T1 signal (typically iso- to hypointense but hyperintense if melanotic or hemorrhagic) and variable T2 signal (moderately hyperintense, very hyperintense if mucinous/condroid, or hypointense if fibrotic).
  • MRI with gadolinium shows moderate homogeneous or heterogeneous enhancement and is more sensitive than CT for detecting perineural spread, orbital invasion, and intracranial extension.
  • DWI/ADC sequences indicate cellularity: malignant lesions typically have lower ADC values than benign lesions, with the lowest values in very hypercellular tumors such as sinonasal lymphoma.
  • MRI can distinguish tumor from trapped secretions, which is a key advantage over CT for assessing local invasion and intraluminal disease.
  • PET-CT shows intense FDG avidity in most sinonasal malignancies and is useful for detecting nodal and distant metastases.
  • Common histologies include squamous cell carcinoma (most common), salivary gland tumors especially adenoid cystic carcinoma (second most common), and sinonasal adenocarcinoma (third most common).
Differential Diagnosis
  • Benign sinonasal pathologies (polyps, mucoceles, sinusitis): distinguished by absence of bony erosion, lack of enhancement, and clinical presentation without constitutional symptoms.
  • Sinonasal lymphoma: very hypercellular with lowest ADC values, homogeneous attenuation/signal, often avid on PET, but may be less destructive of bone than carcinomas.
  • Olfactory neuroblastoma: typically arises in the cribriform region and olfactory region near the superior nasal septum, with potential for early intracranial extension.
  • Rhabdomyosarcoma: occurs in younger patients, shows rapid growth, hypercellular appearance with low ADC values, and may have less bone erosion initially.
  • Juvenile nasopharyngeal angiofibroma: highly vascular with intense enhancement, serpiginous flow voids, proclivity for posterior nasopharynx, and occurs in adolescent males.
  • Mucosal melanoma: hyperattenuating or hyperintense on T1 due to melanin, high FDG avidity on PET, and typically presents in older patients with poor prognosis.
Discussion

Clinical presentation of sinonasal malignancies is non-specific and overlaps significantly with benign conditions, leading to delayed diagnosis; high index of suspicion is needed in patients with persistent or progressive sinonasal symptoms.

Imaging is essential for local staging, assessment of resectability, surgical planning via open versus endoscopic approaches, and detection of metastatic disease; however, imaging alone often cannot determine the specific histologic type.

MRI is superior to CT for assessing soft tissue invasion including orbital extension, intracranial involvement, and perineural spread, which are critical for treatment planning and prognosis.

Treatment is multimodal and typically involves surgical resection with negative margins as the cornerstone, often supplemented by postoperative radiotherapy for high-grade or incompletely resected tumors.

Histologic diversity of sinonasal malignancies (carcinomas, sarcomas, and other rare tumors) means that biopsy confirmation is essential before treatment planning, even when imaging is concerning.

Emerging therapies including immunotherapy and targeted agents are under investigation but remain individualized based on histology and molecular subgrouping.

Reporting Pearls

Clearly describe the location and extent of the mass, specify the presence and location of bony erosion or invasion (using anatomical landmarks such as cribriform plate, orbits, or pterygopalatine fossa), assess for perineural spread along named nerves on MRI, document intracranial extension and orbital involvement, and note any cervical lymphadenopathy or distant metastases; use this structured assessment to guide the multidisciplinary team's surgical and treatment planning.

Pitfalls
  • Confusing benign secretions or mucinous material with tumor extent on imaging; MRI can help distinguish these but clinical correlation and endoscopy are essential.
  • Underestimating bone involvement by relying solely on MRI; CT must be reviewed for accurate assessment of bony erosion and integrity, which are crucial for surgical planning.
  • Assuming a specific histologic diagnosis based on imaging alone, which can lead to incorrect treatment planning; biopsy confirmation is mandatory before definitive therapy.
  • Missing perineural spread on MRI if specific attention is not paid to the course of named nerves (V2, V3, CN II, etc.) and the presence of nerve enlargement or signal abnormality along their course.
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