Chapter 43 - Primary and Metastatic Pulmonary Neoplasia

Question 1

Hypertrophic osteopathy (HO) is a condition reported in dogs with primary and metastatic pulmonary neoplasia. What are the most common clinical signs of this condition?

Answer 1

limb swelling and lameness (ocular discharge, episcleral injection and lethargy were also reported)

Question 2

List clinical signs of primary or metastatic lung tumors including non-specific signs.

Answer 2

1. Coughing, exercise intolerance, increased respiratory rate, or dyspnea
2. Weight loss, lethargy, anorexia
3. Primary lung tumors may be detected as an incidental findings with no clinical signs.

Question 3

Why is a CT scan better than thoracic radiographs in pulmonary neoplasia?

Answer 3

1. Evaluation of intrathoracic lymph nodes (superior sensitivity and specificity for identifying tracheobronchial lymph node status) and other lung fields for small metastatic lesions that are not visible on radiographs.
   However, the CT scan will not necessarily distinguish between neoplastic and benign lesions.
2. Performing a CT scan prior to surgery can help with surgical planning and estimating the likelihood of complete surgical removal of the mass.
3. If neoplastic effusion is suspected, a CT scan can be helpful to better evaluate the presence of pleural masses prior to pursuing thoracic surgery.

Question 4

List differential diagnoses for dogs and cats with neoplastic pleural effusions

Answer 4

round cell tumor (lymphoma, mast cell tumor), carcinomatosis, mesothelioma

Question 5

Why is it difficult to distinguish between carcinomatosis and mesothelioma based on cytology of fluid alone?

Answer 5

Normal mesothelial cells will proliferate and exhibit dystrophic changes when exposed to effusion.
It is often not possible to determine if any abnormal cells seen are reactive or neoplastic mesothelial cells based on cytology alone. The next step is to sample the lesions via biopsy or fine needle aspiration, depending on the location of the masses.

Question 6

If surgery is not pursued in dogs with primary lung tumors, what should supportive care include?

Answer 6

Antitussives, non-steroidal anti-inflammatory drugs, and pain management
Pain management is essential for patients with hypertrophic osteopathy

Question 7

List prognostic factors for dogs with primary lung tumors.

Answer 7

Increasing tumor size (larger than 100cm3), presence of clinical sings, and presence of lymph node metastasis or multiple pulmonary tumors. Overall, the expected survival following surgery for dogs with primary lung tumors is varied (from months to years after surgery)

Question 8

What is the prognosis for cats with primary lung tumors with digit metastasis?

Answer 8

Extremely poor (median survival times of 28 and 67 days reported). Treatment beyond palliative care and eventual euthanasia is rarely recommended.

Question 9

What is the mainstay of treatment for primary lung tumors in dogs and cats?

Answer 9

Surgical resection

Question 10

Treatments for mesothelioma?

Answer 10

1. No definitive therapy is currently available for dogs or cats with mesothelioma. All treatments are aimed at palliating the clinical signs associated with the pleural effusion. (Oxygen supplementation, thoracocentesis, and analgesics, glucocorticoids or non-steroidal anti-inflammatory medications)
2. Intracavitary chemotherapy with cisplatin was reported in dogs and the resolution of the effusion was noted.