IN THE LAB
1 Where did the white cells go? Genevieve D’Amours, from SVS Laboratories, Ian Millward, from Veterinary Referral Services and Sara Bruce, from Cambridge Pet Vets consider the case of a cat with a severe and persistent neutropenia. STARSKY, A 13-YEAR-OLD male domestic short-hair cat, was taken to his veterinarian because of weight loss in the previous two or three months. He was tachycardic and hyperthyroidism was suspected. On serum biochemistry there was a mild increase in globulins at 53g/L (reference range 27–49) and the alkaline phosphatase was mildly elevated at 114U/L (reference range 0–85), but the T4 was normal at 22nmol/L (reference range 20–40). Haematology showed a
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severe neutropenia, with neutrophils at 0.2 x109/L (reference range 1.5–10.8) with no left shift. There was no anaemia or thrombocytopenia. A week later, the neutropenia was still present at 0.4 x109/L. Chest radiographs indicated a 3cm x 6cm ovoid soft tissue mass in the cranial mediastinum, extending from the second to the fifth rib, with contact on the dorsal aspect of sternebrae 2–5 and causing border effacement of the cranial aspect of the cardiac silhouette. On ultrasonography the mass had soft tissue
FIGURE 1: Fine needle aspirate of mediastinal mass. Rafts of epithelial cells with pale cytoplasm and indistinct cell borders. Occasional small lymphocytes are present in the background. Mast cells were also present (not shown here).
echogenicity with some fluid pockets. An ultrasound-guided fine needle aspirate of the mass was taken. On cytology there was a mixed population of cells consisting mainly of large rafts of poorly preserved epithelial cells. The cells had pale cytoplasm and indistinct cytoplasmic borders and ovoid nuclei with fine chromatin and single small nucleolus (Figure 1). Scattered throughout the rafts was a moderate number of heavily granulated mast cells. Around the rafts of epithelial cells was a moderate number of small to medium lymphocytes with occasional large lymphocytes. There were also occasional large, foamy macrophages containing dark pigment and rare, plump, fusiform mesenchymal cells. Occasional cholesterol crystals were present in the background.
IMAGERY: SUPPLIED
