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Singh et al. Mini-invasive Surg. 2025;9:28 https://dx.doi.org/10.20517/2574-1225.2024.75 Page 13 of 25

SINONASAL SQUAMOUS CELL CARCINOMA
Sinonasal squamous cell carcinomas (SNSCCs) account for 61% of all sinonasal malignancies. The maxillary
[28]
antrum is the most common site of origin, followed by the nasal cavity and ethmoid air cells . SNSCCs are
classified into keratinizing and non-keratinizing subtypes, which share overlapping imaging features but
differ slightly in their preferred locations. Both subtypes are frequently encountered in the maxillary antrum
and nasal cavity; however, keratinizing SNSCCs are more likely to arise in the nasal vestibule . Non-
[25]
keratinizing SNSCCs are associated with HPV type 16, which is linked to higher incidence and improved
overall survival [25,28] . A newly recognized subtype of non-keratinizing SNSCCs, DEK-AFF2-rearranged
carcinoma, demonstrates a predilection for the posterior portion of the middle turbinate .
[25]
The imaging features of SNSCCs reflect their aggressive biological behavior, typically showing bone
destruction and extensive locoregional invasion, including perineural spread as well as orbital and
[29]
intracranial extension . CT and contrast-enhanced MRI are essential for evaluating osseous involvement
and for comprehensive tumor mapping . On MRI, lesions often demonstrate intermediate signal intensity
[28]
on both T1- and T2-weighted sequences and reduced ADC values [Figure 19] [28,29] . If the tumor spreads to
regions with rich lymphatic drainage, such as the nasopharynx or hard palate, it can metastasize to the
cervical chain and lateral retropharyngeal lymph nodes .
[30]

HPV-related multiphenotypic sinonasal carcinoma is a recently recognized entity included in the 2022
WHO classification of head and neck cancers. It demonstrates a propensity for the nasal cavity, particularly
the turbinates . This tumor is linked to high-risk HPV type 33 and is distinct from HPV-positive SNSCCs.
[25]
Unlike other HPV-related head and neck carcinomas, it has not been reported to present with cystic nodal
metastasis .
[31]

SINONASAL ADENOCARCINOMA
Sinonasal adenocarcinoma (SNAC) is a rare malignancy of the sinonasal tract that arises from the
respiratory surface epithelium or the underlying seromucinous glands. These tumors are classified into
salivary-type and non-salivary-type . Histologically, salivary-type SNAC resembles tumors arising in the
[32]
salivary glands and accounts for 5%-10% of all SNACs . Tumor subtypes include AdCC, myoepithelial
[32]
carcinoma, and acinic cell carcinoma. Among these, AdCC is the most common salivary-type SNAC and
represents the second most common sinonasal malignancy overall, after SCC . AdCC typically occurs in
[32]
the maxillary antrum or nasal cavity and is associated with a poor long-term prognosis due to local invasion
and perineural spread [Figure 20] [16,32] .

Non-salivary-type SNACs are subdivided into intestinal and non-intestinal types. Intestinal-type SNACs,
[32]
the second most common form of SNAC , histologically resemble carcinomas of intestinal origin. These
aggressive tumors most frequently arise in the ethmoid air cells, followed by the nasal cavity and maxillary
[16]
antrum . At diagnosis, they commonly show local extension into the orbit, PPF, and cranial cavity .
[32]
Non-intestinal-type SNACs are distinct from both salivary and intestinal types in terms of histology. These
rare, heterogeneous tumors display diverse morphological patterns, commonly occur in the ethmoid air
cells and nasal cavity, and are associated with poor prognoses .
[32]

MR imaging of SNAC is primarily used for tumor mapping and assessment of submucosal involvement,
local invasion, perineural spread, and bone infiltration. However, the signal characteristics on both CT and
MR images are often nonspecific and generally do not enable reliable differentiation of SNAC from other
[16]
sinonasal malignancies .