Case Study

CT – Primary malignant neoplasia of the 5th-7th rib, CHF and metastases in a 2 year old FS American Bulldog

This 2 year old FS American Bulldoghas a history of a large mass of the right thoracic wall deviating heart to the left, possible right sided heart failure. Ascites drained for the second time.

CBC/Chem: WBC 22,200, ALP 816

U/A: WBCs 40-60/hpf, protein +1, pH 8

This 2 year old FS American Bulldoghas a history of a large mass of the right thoracic wall deviating heart to the left, possible right sided heart failure. Ascites drained for the second time.

CBC/Chem: WBC 22,200, ALP 816

U/A: WBCs 40-60/hpf, protein +1, pH 8

DX

• Primary malignant neoplasia of the right 6th rib involving the 5th and 7th rib • Congestive failure of the rightsided low pressure system of the heart and caudal vena cava syndrome owing to the mass effect of the tumor • Metastatic spread to the sternal and cranial mediastinal lymph nodes

Image Interpretation

CT of the thorax and abdomen –

Thorax: A large ovoid soft tissue attenuating mass with focal mineralizations is emerging from the right 6th rib. The mass measures 15 x 20 x 10 cm and mainly expands centrifugally into the pleural cavity. There is a marked mass effect onto the right lung with compression atelectasis and a marled mass effect onto the heart which is pushed into the left hemithorax and compressed against the left chest wall. The intrathoracic caudal vena cava is pushed to the left as well and presents narrowing by more than 50 % of its cross sectional area as well as marked kinking level with the diaphragm. The intraabdominal caudal vena cava is dilated. Multifocal permeative agrressive osteolysis of the 6th right rib is noted as well as amorphous periostel reactions. The 5th and 7th rib present aggressive osteolytic and osteoproliferative changes as well. The sternal and cranial mediastinal lymph node present marked asymmetric enlargement with increased short-to-long axis and irregular enhancement pattern.

Abdomen:

A large amount of free peritoneal effusion is seen as well as dilation of the caudal vena cava and hepatic veins, gallbladder wall edema and generalized hepatomegaly.

Outcome

The most likely diagnosis is a chondrosarcoma or osteosarcoma of the rib. Other less likely differentials include a fibrosaroma or hemangiosarcoma.
The progonsis varies significantly between the aforementioned tumor types. The prognosis is much more favorable in an osteosarcoma as compared with a chondrosarcoma. However, the metastatic spread makes the diagnosis of an osteosarcoma less likely and worsens the prognosis.

Palliative surgical resection of the tumor may be considered to alleviate the clinical signs of congestive heart failure/cava syndrome versus full tumor staging with biopsy to gain a more comprehensive overview on the prognosis and tailor treatment options such as surgery/chemotherapy/radiation therapy adequately to the tumor type.