Computed tomographic features of thymoma in the dog: a case report and review of eight cases.

CASE REPORT A well-demarcated 18 x13 x 16 cm (H x W x L) mediastinal mass with lobulated contour and heterogeneous attenuation was demonstrated on computed tomographic (CT) images of an 11.5-year-old female Labrador Retriever crossbred dog admitted with a history of coughing, polyuria and polydipsia. After intravenous contrast administration, faint, non-uniform enhancement of the mass was noted. The mass was in contact with the parietal pleura, aortic arch, pulmonary trunk and right atrium, but no signs consistent with invasion of the adjacent structures were evident. The mass was surgically excised and absence of any intrathoracic visceral invasion was confirmed. Histopathologically, the mass was reported to be a thymoma. DISCUSSION CT findings and invasiveness of thymomas in eight other cases found in the literature are included and discussed in the present report. CT is useful for demonstrating the invasiveness of a thymoma in dogs. Invasion of the mediastinal blood vessels should be considered a CT feature of invasiveness, but false-positive and false-negative diagnoses do occur. [ABSTRACT FROM AUTHOR]