PMC10064164_01
Transverse CT of the cat at diagnosis. (a,b) The rostral aspect of the nose at (c,d) the level of the orbit and (e,f) the level of the cribriform plate at the initial presentation; (b,d,f) post intravenous iodinated contrast agent administration. The tumour lesion filled the entire the right nasal cavity with subcutaneous (arrows), orbital and frontal sinus invasion. Lysis of the cribriform plate was also seen (arrowhead)
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Contrast-enhanced whole-body CT and MRI were performed under general anaesthesia on day 2 at the referring institution (ER Bunkyo, Tokyo, Japan), which identified a mass filling the entire right nasal cavity, measuring 4.9 cm (longest diameter), with subcutaneous, orbital and right frontal sinus invasion and lysis of the cribriform plate (Figures 1 and 2).
MRI of the cat at diagnosis: (a) T2-weighted, (b) fluid-attenuated inversion recovery (FLAIR), (c) T1-weighted and (d) T1-weighted postcontrast images were obtained. The mass in the sinonasal cavity was hypointense-to-isointense in T1-weighted images and isointense-to-hyperintense in T2-weighted and FLAIR images. The lesion was heterogeneously enhanced in the postcontrast image
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Contrast-enhanced whole-body CT and MRI were performed under general anaesthesia on day 2 at the referring institution (ER Bunkyo, Tokyo, Japan), which identified a mass filling the entire right nasal cavity, measuring 4.9 cm (longest diameter), with subcutaneous, orbital and right frontal sinus invasion and lysis of the cribriform plate (Figures 1 and 2).
Transverse CT of the level of the (a,c,e,g) maxillary third premolar and (b,d,f,h) frontal sinus. (a,b) At the initiation of radiotherapy (RT), the tumour in the right nasal cavity was markedly reduced following treatment with L-asparaginase and prednisolone. (c,d) Four months after RT, a lesion enlargement in the right nasal cavity, which was suspected to be a recurrent lesion of the nasal tumour, was observed despite receiving RT followed by cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP)-based chemotherapy. (e,f) One month and (g,h) 4 months after rescue chemotherapy with chlorambucil, the presumed recurrent lesion gradually reduced in size in the right nasal and frontal sinus
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The clinical target volume included regions at risk for microscopic disease based on CT at diagnosis (day 2), as CT revealed a marked tumour reduction in the right nasal cavity at the time of the radiotherapy (Figure 3a,b). Follow-up CT performed 3 months after completion of radiation therapy as planned (day 116) revealed enlargement of the lesion in the right nasal cavity vs the time of radiotherapy planning, which was suspected to be a recurrent sinonasal lymphoma (Figure 3c,d), although there had been no clinical signs suggestive of tumour relapse between the time of initiation of radiotherapy and the first follow-up CT. Follow-up CT performed 31 days after the initiation of treatment with chlorambucil (day 151) demonstrated a 55% volume reduction in the presumed recurrent lesion of the tumour (Figure 3e,f), and the general condition of the cat was good, without nasal discharge. CT on day 109 post-treatment with chlorambucil (day 229) revealed an 80% volume reduction in the presumed recurrent lesion of the tumour vs the tumour volume on day 116 (Figure 3g,h), and no evidence on imaging of disease relapse in the organs, including the brain, mandibular and medial retropharyngeal lymph nodes, liver, kidneys and spleen.