RESUMO
SMARCB1 deficient sinonasal carcinomas are rare neoplasms, classified under sinonasal undifferentiated carcinomas by the fourth edition of the World Health Organization (WHO) classification of head and neck tumors. It is characterized immunohistochemically by loss of SMARCB1(INI1) expression. We are reporting the case of a 63-year-old man who was evaluated for nasal stuffiness of 3 months duration in another hospital where a radiological evaluation showed a polypoidal soft tissue lesion in the right maxillary sinus extending to the right nasal cavity and spheno-ethmoidal sinus. He underwent excision biopsy which was reported as non- keratinizing nasopharyngeal carcinoma. He was referred to our center with residual disease in spheno-ethmoidal recess for which radiotherapy was given. After completion of radiotherapy, the primary site had no residual disease, but while on follow-up he developed left sided neck nodes within 4 months of completion of treatment. Excision of the lesion was done and histopathological and immunohistochemical analysis revealed it to be metastasis from SMARCB1 deficient sinonasal carcinoma and not nasopharyngeal carcinoma as diagnosed from the other center. This case is being reported to highlight the diagnostic challenge associated with this rare entity.
RESUMO
Objective:To assess the clinical and imaging features of SMARCB1-deficient sinonasal carcinoma.Methods:Form January 2016 to November 2021, the clinical data and pretreatment imaging findings of 16 cases with pathologically proven SMARCB1-de?cient sinonasal carcinomas were analyzed retrospectively in Beijing Tongren Hospital, Capital Medical University. Immunohistochemistry for SMARCB1 showed loss of the protein in the tumor nuclie. Clinical and imaging features, including tumor location, TNM stage, size, density of CT, bone change, MRI signal intensity, enhancement pattern, type of time-intensity curve (TIC) of dynamic contrast enhanced MRI (DCE-MRI), apparent diffusion coefficient (ADC) value and diffusion weighted imaging (DWI) were evaluated. For 14 cases, correlation of the ADC value and Ki-67 index was subsequently evaluated with Pearson correlation analysis.Results:For the 16 cases SMARCB1-deficient sinonasal carcinomas, clinical stage of T4 was 12 cases and T3 was 4 cases. The location included ethmoid sinus ( n=4), nasal cavity only ( n=1), both nasal cavity and ethmoid ( n=8), ethmoid and maxillary sinus ( n=1), ethmoid and frontal sinus ( n=1), ethmoid and sphenoid sinus ( n=1). The tumor size was (4.5±1.2) cm. Iso-attenuated of CT images was showed in 13 cases and heterogeneous with necrosis was showed in 3 cases. Focal bone erosion was found in 13 cases and extensive bone destruction was found in 3 cases. Compared with adjacent muscles, T 1WI of all 16 cases showed isointense, with focal hypointense in 3 cases. On T 2WI, the tumor was graded as isointense in 9 cases, hyperintense in 7 cases, with lower inner septal in 6 cases. Enhancement was graded as mild in 11 cases, moderate in 5 cases.MRI Enhancement images showed mild enhancement in 11 cases, moderate enhancement in 5 cases, heterogeneous enhancement in 6 cases, and homogeneous enhancement in 10 cases. For DCE-MRI of 14 cases, there were 10 cases of Ⅲ type and 4 cases of Ⅱ type of the TIC. The ADC value of 14 cases was (1.02±0.27)×10 -3 mm 2/s. The Ki-67 index was 48%±21%. No correlation was observed between Ki-67 index and ADC value ( r=-0.38, P=0.183). Conclusions:SMARCB1-deficient carcinomas are mostly centered in the nasal and ethmoid region of anatomic distribution. Tendency to be infiltrative the adjacent bone structure with invasive bone reaction, mild to moderate heterogeneous enhancement, T 2WI with lower inner septal, and Ⅲ types of TIC are certain suggestive imaging features of the entity.