Veterinary Medicine - March 2008 - (Page 164)

Primary lung tumors PEER-REVIEWED 8. A lateral thoracic radiograph of the cat in Figure 6 identiﬁes a soft tissue opacity (arrows) involving the left caudal lung lobe. (Photograph courtesy of Dr. Laura Garrett.) node status, it did appear, as in dogs, that draining lymph node involvement may correlate with survival time, as 12 cats without enlarged tracheobronchial lymph nodes survived for a median of 412 days, whereas four cats with enlarged lymph nodes survived only a median of 73 days.27 In addition to histologic differentiation and lymph node enlargement, digital metastasis in cats with primary lung tumors is a poor prognostic nding. Cats with digital metastases have an average survival of 4.9 weeks (median 4 weeks) compared with a survival of 29.5 weeks (mean 12.5 weeks) in cats with primary digital squamous cell carcinoma.42 9. A ﬁne-needle aspirate of a pulmonary mass identiﬁes a cohesive population of basophilic, epithelial cells with squamous differentiation in a background of suppurative inﬂammatory cells. Multiple criteria of malignancy are evident, including anisocytosis and an increased nuclear to cytoplasmic ratio, consistent with primary pulmonary squamous cell carcinoma. Pulmonary squamous cell carcinoma is often associated with metastasis to the digits in cats. (Wright’s stain, 500X). (Photograph courtesy of Dr. Laura Garrett.) hypertrophic osteopathy.1 Single case reports of paraneoplastic syndromes have been suggested in cats, including marked leukocytosis in a cat with squamous cell carcinoma, hypercalcemia with bronchogenic adenocarcinoma, and thrombocytosis with bronchoalveolar carcinoma.45-47 TREATMENT The treatment of choice for solitary primary pulmonary tumors in dogs and cats is wide surgical resection—either a complete lung lobectomy or a partial lobectomy if the tumor is in the periphery.27,48 However, in cats more often than dogs, even if a single pulmonary nodule is seen radiographically, it is not uncommon to nd multiple small lesions at surgery, suggesting the importance of advanced diagnostic imaging (CT or magnetic resonance imaging) before surgery.1 PARANEOPLASTIC SYNDROMES In a retrospective study of 210 dogs with primary lung tumors, paraneoplastic syndromes were observed, but their frequency was low (< 6%): Six dogs had radiographic signs of hypertrophic osteopathy (2.9%) (Figure 10), two dogs were hypercalcemic, two dogs had a fever, and two dogs had tumorinduced secretion of adrenocorticotropic hormone (ACTH).4 From other investigations, the development of hypertrophic osteopathy in dogs with primary lung tumors has been re- Surgery ported to range from 4% to 17%.2,12 Overt lameness and pain Given the advent of beroptic technologies and the training in dogs with primary lung tumors may not always indicate of surgical residents in noninvasive techniques, thoracoscopic hypertrophic osteopathy, as skeletal metastasis could also lung lobectomy is becoming a more common surgical apcause similar clinical signs of pain and discomfort. Other proach for managing lung tumors in companion animals. less frequent hematologic paraneoplastic syndromes asso- When compared with thoracotomy in people, the results of ciated with primary lung tumors in dogs include absolute thoracoscopy are less tissue trauma, decreased morbidity, erythrocytosis and leukocytosis.43,44 shorter hospitalization, and earlier return to normal activity.49 Paraneoplastic syndromes in cats occur even less frequently. Adequate exposure of the thoracic cavity and access to the hilar In a study of 86 cats with primary lung tumors, none of the lymph nodes may still require conventional thoracotomy, so patients experienced paraneoplastic syndromes.16 Although thoracoscopic procedures are best suited for removing small, lameness may be a common presenting sign (25% in one peripherally located masses.48 For conventional thoracotomy, a lateral intercostal surgical study), it is usually indicative of bone metastases rather than 164 March 2008 VETERINARY MEDICINE

Table of Contents Feed for the Digital Edition of Veterinary Medicine - March 2008

Veterinary Medicine - March 2008 Contents Toxicology Brief Idea Exchange A Challenging Case An Update on Diagnosing and Treating Primary Lung Tumors CE Form Product Preview Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - March 2008

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