Cranial Mediastinal Mass in an Old Dog
History: An 11 year-old, spayed female Labrador retriever presents for polyuria and polydipsia. The owners report mild lethargy but the dog is otherwise doing well. Physical examination reveals body condition 4/9 but is otherwise within normal limits for a dog of this age. A complete blood count is within normal limits. The chemistry profile reveals total calcium 15.4 mg/dl (NR, 9.4-11.8), ionized calcium 1.7 mmol/L (NR, 1.12-1.40), creatinine 2.1 mg/dl (NR, 0.6-2.0), BUN 39 mg/dl (NR, 8-30). Urinalysis reveals dilute urine with a specific gravity of 1.008. Thoracic radiographs are taken (Figure 1) and an ultrasound-guided fine needle aspiration is performed..
What are the differential diagnoses for this lesion?
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