Clinical Case Challenge

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..

Figure 1: Lateral thoracic radiograph demonstrating cranial mediastinal mass.

What are the differential diagnoses for this lesion?

Figure 2: Cytology of cranial mediastinal mass. Green arrows point to mast cells.

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Answers

Clinical Case Challenge September 2011: Answers

Clinical Case Challenge September 2011

  • Answer 1: A 4cm long echogenic lesion most consistent with a thrombus is visualized within the portal vein.
  • Answer 2: pancreatitis, acute enteritis, septic peritonitis, gastrointestinal foreign body, portal vein thrombosis
  • Diagnosis: Portal Vein Thrombosis

    Treatment for shock was initiated using 90ml/kg LRS IV. Tachycardia persisted despite the initial bolus, and a recheck lactate was 5.4 mmol/L. Following administration of 20ml/kg Voluven and an additional 45ml/kg LRS IV, the heart rate stabilized and lactate concentration normalized. The dog was hospitalized for ongoing support, and heparin was initiated (Fragmin 150u SQ BID). The dog was discharged 2 days later with instructions related to initiating a tapering dose of prednisone.