Case Study

CT Mesenchymal Soft Tissue Neoplasia on Thoracic Wall, with Reactive Pleuritis in a 13 year old Terrier Dog

Owner noticed slow growing mass the last 2-3 months, located on the right lateral thorax. It was initially associated with right forelimb lameness, but the patient is not currently lame. A biopsy of the mass was obtained. Physical Exam: Large mass on right lateral thoracic ventral wall CBC and chemistry were WNL.

Image Interpretation

CT of the thorax, plain and post contrast – There was a large, well delineated ovoid subfascial soft tissue attenuating mass exhibiting weak non uniform peripheral contrast enhancement on the right ventral and mid thoracic wall extending from the 4th to the 10th rib. The mass had a significant mass effect deviating the rib cage, intercostal muscles and parietal pleura medially. Mild even pleural thickening was noted. There was pressure related atrophy of the 5th to 7th right rib and intercostal muscles. No aggressive bone lysis was seen.
There was anesthesia related atelectasis in the dependent portion of the lung. No sign of lung or lymph node metastases was noted.

DX

mesenchymal soft tissue neoplasia causing pressure related bony and muscular atrophy as well as reactive pleuritis.

Outcome

Specific malignancy criteria are not developed so that both malignant and benign neoplasia has to be considered. Differentials include fibroma/fibrosarcoma/neurofibrosarcoma/lymphosarcoma and other. The findings are not typical for an osteo- or chondrosarcoma.
Sampling is essential in further workup and treatment planning and was recommended.