Veterinary Medicine - September 2008 - (Page 492)

PEER-REVIEWED A challenging case: Thymic cyst and recurrent chylothorax in a cat Continuing pleural effusion caused repeated episodes of dyspnea and necessitated two separate surgeries in this patient. Peter Nurre, DVM, DACVIM; Roger Johnson, DVM, DACVIM; Kevin Bissonnette, DVM, MS; and Carl Koehler, DVM, DACVS A Vital Stats Signalment • 13-year-old male castrated 14.7-lb domestic longhaired cat History and presenting complaints • Dyspnea of one week’s duration • History of dyspnea due to a cranial mediastinal cyst with ﬂuid buildup that had been relieved by ultrasound-guided aspiration two months earlier Initial diagnostic ﬁndings 13-year-old castrated male domestic longhaired cat had been presented to the referring veterinarian for evaluation of dyspnea and listlessness of two days’ duration. The cat weighed 14.5 lb (6.6 kg), was eupneic, and appeared to be stable. The results of a complete blood count, serum chemistry pro le, and total thyroxine (T4) concentration had been unremarkable. Thoracic radiography had revealed a cranial mediastinal mass. The referring veterinarian had released the cat to its owner with instructions to return for thoracic ultrasonography two days later. The ultrasonographic examination had revealed a uid- lled, thick-walled structure in the cranial mediastinum that measured 4.2 cm in diameter and had an irregular wall up to 1.5 cm thick. Aspiration of the mass had yielded 25 ml of dark-brown uid, and the results of cytologic examination had been consistent with cystic material. No neoplastic cells had been observed. The veterinarian had discussed a referral for further evaluation of the cranial mediastinal cyst, but the owner had declined. No treatment had been prescribed. 60 breaths/min, and its heart rate was 180 beats/min. Thoracic auscultation revealed no lung sounds ventrally, and the heart sounds were heard more caudal than usual. The rest of the physical examination ndings were unremarkable. Diagnostic tests A thoracic ultrasonographic examination revealed a 7-cm-diameter cranial mediastinal cystic lesion and severe pleural effusion. Thoracentesis yielded 400 ml of milky uid from the right side. In addition, 50 ml of dark uid was removed from the cyst by ne-needle aspiration from the left side, which reduced the cyst’s volume by about half. After these procedures, the cat was eupneic. Thoracic radiographs obtained after the cyst was drained revealed a soft tissue opacity in the cranial mediastinal region (Figures 1A & 1B). The cardiac silhouette and lung pattern were unremarkable, and a small amount of pleural uid was noted. Two-dimensional echocardiography revealed no evidence of left ventricular eccentric or concentric hypertrophy. The cat’s systolic function was normal, as were the left atrial size and the left atrial-to-aortic ratios. No abnormalities were identi ed on color ow and Peter Nurre, DVM, DACVIM Roger Johnson, DVM, DACVIM Kevin Bissonnette, DVM, MS Carl Koehler, DVM, DACVS East Bay Veterinary Specialists and Emergency 2803 Ygnacio Valley Road Walnut Creek, CA 94598 • Thoracic ultrasonography revealed a cranial mediastinal cyst and pleural effusion • Normal echocardiographic ﬁndings INITIAL PRESENTATION Two months later, the cat was referred to East Bay Veterinary Specialists for evaluation of a one-week history of dyspnea. On physical examination, the cat was dyspneic with an increased inspiratory effort. The cat weighed 14.7 lb (6.7 kg) and had a body condition score of 5 out of 9. Its mucous membranes were pink, the capillary re ll time was < 1 sec, and its temperature was 99.8 F (37.7 C). The cat’s respiratory rate was Initial suspicions mediastinal cyst • Idiopathic chylothorax • Chylothorax due to a cranial 492 September 2008 VETERINARY MEDICINE Getty Images

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Veterinary Medicine - September 2008 Contents Leading Off Practical Matters Idea Exchange A Challengin Case: Thymic Cyst and Recurrent Chylothorax in a Cat 10 Life-Threatening Behavior Myths CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - September 2008

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