Thoracic wall masses are often described as being iceberg lesions, with the size of the thoracic wall component unrepresentative of the true size of the mass. The advent of tomographic imaging techniques has improved the assessment of mass lesions in veterinary practice and thoracic wall lesions should be prime candidates for useful assessment with computed tomography (CT). The aim of this retrospective study was to review the CT features and determine the usefulness of CT in the diagnosis of thoracic wall masses in dogs and cats.

The case records and images of all the animals (11 dogs and 2 cats) which underwent thoracic CT for investigation of a thoracic wall mass between July 2004 and August 2007 were reviewed. Three of the cases also had thoracic radiographs available for comparison.

All thirteen animals had spiral CT examination of the thorax. Slice thickness and pitch were 8mm and 0.75:1 for the dogs and 5mm and 1:1 for the cats. Ten cases had the CT examination repeated after intravenous administration of ionic iodine-containing contrast medium. CT allowed identification of: degree of body wall involvement; number and position of affected ribs; extent of the intrathoracic component; and presence of intrathoracic disease, including pulmonary metastases. Pulmonary metastases were identified in two cases. Twelve cases had a final histopathological diagnosis: chondrosarcoma (5), osteosarcoma (3), undifferentiated sarcoma (2), haemangiosarcoma (1), lipoma (1).

CT examination enables assessment of chest wall lesions and any associated intrathoracic disease in a single study. Multiplanar (MPR) and three dimensional (3DR) reconstructions of the data provide useful images for surgical planning and any adjuvant therapy such as radiation. Contrast CT provides extra information for incisional biopsy planning and pulmonary metastasis identification. Potential limitations include difficulties in accurate identification of the site of the lesion using transverse plane slices alone, and in some situations a single thoracic radiograph may be needed to localise the lesion accurately in the absence of access to MPR or 3DR, although the scout image may be used as a conventional radiograph.