Mediastinal Fibrosarcoma in a Dog-Case Report.

Alysha M Mcgrath,Eric T Hostnik,Alycen P Lundberg,Laura E Selmic,Janis Lapsley,Giovanni Tremolada,Sarah A Salyer,Melissa R Leonard,Joshua N Lorbach,Sarah Lumbrezer-Johnson,Amanda Seelmann

doi:10.3389/fvets.2022.820956

Alysha M Mcgrath, Eric T Hostnik + Show 9 more

Open Access

https://doi.org/10.3389/fvets.2022.820956

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Abstract

This represents the first published case report of mediastinal fibrosarcoma in a dog. An 8-year-old male neutered mixed breed dog was presented for evaluation of lethargy and increased panting. Thoracic focused assessment with sonography for trauma revealed moderate pleural effusion. Thoracic radiograph findings were suggestive of a cranial mediastinal mass. Computed tomography revealed a mass within the right ventral aspect of the cranial mediastinum. On surgical exploration, a cranial mediastinal mass with an adhesion to the right cranial lung lobe was identified and removed en-bloc using a vessel sealant device and requiring a partial lung lobectomy. Histopathology results described the cranial mediastinal mass as fibrosarcoma with reactive mesothelial cells identified within the sternal lymph node. The patient was treated with systemic chemotherapy following surgical removal. To date, the dog has survived 223 days following diagnosis with recurrence noted 161 days following diagnosis and radiation therapy was initiated. Primary cranial mediastinal fibrosarcoma while a seemingly rare cause of thoracic pathology in dogs, should be considered in the differential diagnosis for a cranial mediastinal mass.

Highlights

Mediastinal masses are commonly diagnosed in dogs and cats [1] and can be categorized by anatomic location including craniodorsal, cranioventral, caudodorsal, caudoventral and hilar with cranioventral overrepresented [2]
The atypical cells within the lymph node were interpreted as reactive mesothelial cells draining to the regional lymph node based on immunolabeling for both cytokeratin AE1/AE3 and vimentin, as well as their characteristic binucleated appearance in which the nuclei are squished together resulting in a flattened appearance of their coalescing borders (Figure 2)
Thoracic radiographs were repeated following three doses of doxorubicin, the results revealed static mild pleural effusion with no signs of metastasis

Summary

INTRODUCTION

Mediastinal masses are commonly diagnosed in dogs and cats [1] and can be categorized by anatomic location including craniodorsal, cranioventral, caudodorsal, caudoventral and hilar with cranioventral overrepresented [2]. Thoracic radiographs were completed post-thoracocentesis revealing a possible cranial mediastinal mass with residual moderate pleural effusion and mild pneumothorax (suspected to be iatrogenic). The atypical cells within the lymph node were interpreted as reactive mesothelial cells draining to the regional lymph node based on immunolabeling for both cytokeratin AE1/AE3 and vimentin, as well as their characteristic binucleated appearance in which the nuclei are squished together resulting in a flattened appearance of their coalescing borders (Figure 2) Given these findings, it was recommended to continue follow-up with the medical oncology service at the University of Illinois. At 155 days following initial diagnosis, the dog presented to the Medical Oncology service for a recheck due to intermittent coughing While his physical examination was unremarkable at that time, thoracic radiographs revealed mildly progressive pleural effusion. The dog has survived 223 days since diagnosis

DISCUSSION

Findings

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