Computed tomographic appearance of canine thyroid tumours

To describe the computed tomography features of canine thyroid tumours. METHODS Retrospective study of records of dogs with a thyroid tumour and neck computed tomography. Neck computed tomographies were evaluated for tumour characteristics. Thoracic radiographs and computed tomographies were evaluated for lung nodules.

Of 19 identified cases, 17 were carcinomas and 2 were adenomas; 12 had mineralisation, 16 had heterogeneous attenuation and 16 were unilateral. Tumours were located from the temporomandibular joint to C5. Sixteen had well-defined margins postcontrast. Tumours were ovoid and mean volume was 57·4 cm(3) . By computed tomography, eight had definitive or possible invasion into surrounding structures; all eight were histopathologically invasive carcinomas. Five histopathologically non-invasive tumours and two adenomas had no computed tomography invasion into surrounding structures. Four had complete palpable mobility (two adenomas and two histopathologically invasive carcinomas); one had computed tomography evidence of possible invasion. The sensitivity of palpable mass mobility to determine histopathological invasion was 71% with 0% specificity. The sensitivity of computed tomography invasion to determine histopathological invasion was 70% with 100% specificity.

Computed tomography scans revealed several common features. Palpable mass mobility was not definitive for lack of histopathological invasion. Computed tomography invasion was specific but not very sensitive for histopathological invasion.