Prevalence of pulmonary nodules in dogs with malignant neoplasia as determined by CT.

In order to estimate the prevalence of pulmonary nodules in dogs with nonpulmonary malignant neoplasia, medical record descriptions of CT findings in dogs diagnosed with nonpulmonary malignant neoplasia were reviewed retrospectively. A total of 536 dogs were sampled from a single hospital. For malignant neoplasms with >10 affected individuals, prevalence of multiple pulmonary nodules at first CT was hemangiosarcoma 24 of 58 (41%), osteosarcoma 14 of 55 (26%), carcinoma 20 of 80 (25%), histiocytic sarcoma five of twenty-one (24%), soft tissue sarcoma 13 of 57 (23%), adenocarcinoma 11 of 60 (18%), melanoma five of thirty-seven (14%), lymphoma 10 of 76 (13%), mast cell tumor two of forty-seven (4%), and squamous cell carcinoma zero of seventeen (0%). A solitary pulmonary nodule was identified at first CT in 33 (6%) dogs. Of these, nine had follow-up CT, including two dogs in which the nodule disappeared, three dogs in which the size of the nodule did not change, and four dogs in which the nodule enlarged and additional pulmonary nodules appeared. Dogs with hemangiosarcoma were most likely to have signs of pulmonary metastasis at first CT, whereas dogs with mast cell tumor were infrequently affected, and no dog with squamous cell carcinoma had signs of pulmonary metastasis. A solitary pulmonary nodule at first CT was an indeterminate finding, potentially unassociated with neoplasia.

Interobserver variability of radiographic pulmonary nodule diameter measurements in dogs and cats.

The purpose of this study was to determine the interobserver variability of radiographic pulmonary nodule diameter measurements among readers with varying levels of experience. Because interobserver variability may lead to inaccurate estimations of nodule growth on repeat radiographic assessment, an incorrect presumption of malignant etiology or misclassification of tumor response to treatment may result. The maximum diameters of 47 pulmonary nodules from 22 dogs and 7 cats were measured. Measurements were performed using one digital thoracic radiographic projection by eight clinicians. The eight clinicians included two interns, two residents, two board-certified veterinary specialists, and two board-certified veterinary radiologists. A mixed-effect analysis of variance model was used to evaluate the contribution of reader, experience level, patient, nodule, and nodule size to the overall variability in mean pulmonary nodule diameter. The interobserver variability in diameter measurement for any given nodule was 16%, and experience level and nodule size classification did not contribute to measurement variability. Linear measurements of the diameter of a pulmonary nodule can vary significantly among a group of clinicians; however, depending on the criteria used to evaluate nodule growth or tumor response, the 16% interobserver variability reported here is likely not clinically significant.

Public health aspects of dirofilariasis in the United States.

Coin lesions in the human lung present significant differential diagnostic problems to the physician. There are at least 20 known causes of such lesions, including neoplastic lesions, infectious diseases, and granulomas. The human medical literature contains many misconceptions about the life cycle of Dirofilaria immitis, including the method of entry of the infective-stage larvae and the development of the young adult worm. These misconceptions have obscured the recognition of the clinical presentation of pulmonary dirofilariasis and the potential for D. immitis to lodge in many other areas of the human body besides the lung. Exposure to infective larvae of D. immitis is more common in humans than is currently recognized. Reported cases in humans reflect the prevalence in the canine population in areas of the United States. The veterinary literature provides compelling evidence that D. immitis is a vascular parasite, not an intracardiac one. Its presence in the right ventricle is a post-mortem artifact, because it has never been shown to be there by echocardiography or angiography in a living dog, even though these techniques have demonstrated adult D. immitis in the pulmonary, femoral, and hepatic arteries; posterior vena cava; and right atrium of live dogs. Physicians have taken the name "heartworm" literally, believing that the worm lives in the heart and only after it dies does it embolize to the pulmonary artery. However, the coin lesion is spherical in shape, not pyramidal, as embolic infarcts to the lung in humans are known to be. The coin lesion is an end-stage result of the parasite's death in the vascular bed of the lungs and the stimulation of a pneumonitis followed by granuloma formation. This pneumonitis phase of human pulmonary dirofilariasis is often not recognized by the radiologist because of the way pneumonitis is diagnosed and treated and because the developing nodule is obscured by the lung inflammation. Serologic methods for use in humans are needed for clinical evaluations of patients with pneumonitis living in highly enzootic D. immitis regions. As well, epidemiological surveys are needed to determine the real extent of this zoonotic infection.