Differentiating Nasal Chondrosarcoma From Nasal Adeno- Carcinoma On Computed Tomography

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Enroth MJ, Marolf AJ, Valdes-Martinez A, et al.

American College of Veterinary Radiologists 2012:102.

Introduction/Purpose: The most common type of nasal tumor in the dog is nasal adenocarcinoma, representing approximately 60% of nasal tumors. Nasal chondrosarcoma is the most common non-epithelial nasal tumor diagnosed in dogs. In veterinary medicine, no definitive criteria have been consistently identified on CT examination to differentiate nasal adenocarcinoma and nasal chondrosarcoma. The purposes of this retrospective study were to: 1) determine if nasal chondrosarcoma was more likely to have internal mineralization than adenocarcinoma 2) evaluate any other unique CT features of nasal chondrosarcoma versus nasal adenocarcinoma to aid in tumor diagnosis.

Methods: Computed tomographic images of 43 dogs with either nasal chondrosarcoma (n=18) or adenocarcinoma (n=25) were evaluated by three board certified radiologists. Criteria evaluated included: nasal cavity involvement, nasal cavity occlusion, sinus involvement, nasal septum lysis or deviation, nasal turbinate lysis, cribriform plate lysis, hard palate lysis, bony and soft tissue expansion, and destruction or alteration of other surrounding bony structures. Additionally evaluated were homogeneity of the mass, contrast enhancement, internal mineralization of the mass and surrounding tissues, and lymph node involvement. Analysis of cross-classification of potential predictors of nasal chondrosarcoma and nasal adenocarcinoma and Fisher’s exact test were performed. P-values of 0.05 or less were considered significant.

Results: In patients with bilateral nasal cavity involvement, bilateral full nasal cavity occlusion was present in 58%(7/12) of chondrosarcoma cases and 11.11%(2/18) cases of adenocarcinoma. Those with both nasal cavities fully occluded were more likely to have chondrosarcoma (p=0.0125). In patients with bilateral nasal cavity involvement, those with one fully occluded nasal cavity occurred in 33.33%(4/12) cases of chondrosarcoma and 66.67%(12/18) cases of adenocarcinoma. Bony expansion and destruction of bone was present in 16%(4/25) of adenocarcinomas and in 38.89%(7/18) of chondrosarcomas. Among tumors with bony expansion present, there were almost twice as many nasal chondrosarcomas as nasal adenocarcinomas. Chondrosarcoma more commonly had internal mineralization. Heterogeneous attenuation of the mass was found in 48%(12/25) of adenocarcinoma cases and 77.78%(14/18) of chondrosarcoma cases (p=0.0637). Among those with homogenous attenuation, there were more than three times as many adenocarcinoma as chondrosarcoma.

Discussion/Conclusion: When comparing CT characteristic of nasal adenocarcinoma versus nasal chondrosarcoma, only weak statistically significant differences were identified. Those tumors with internal mineralization, bony expansion, and bilateral full nasal cavity occlusion were more likely to be chondrosarcoma. Those tumors that were homogeneously attenuating were more likely to be adenocarcinoma. Both tumor types need to be considered as possible differentials when nasal tumors are identified on CT examination.