2. Tumors of the Thoracic Cavity Flashcards
With Chest wall tumors is there sex or breed predisposition? What category and age is represented?
- No sex or breed predisposition
- Large dogs (> 20 kg) seem to be over-represented
- Middle age at presentation = 4.5 - 6 years
What do owners most commonly notice with chest wall tumors?
firm and fixed thoracic wall mass
What CS do you commonly notice with chest wall tumors?
typically non-specific =
- Discomfort
- weight loss
- lethargy
- lameness (if cranial rib affected)
- resp. signs (tachypnea/dyspnea)
When you have a chest wall tumors there are only 2 tumors you need to have in mind which are?
- OSTEOSARCOMA (OSA) = Most common rib tumor in dogs and accounts for 73% of all rib tumors
- 2nd most common = Chondrosarcoma (CSA) way less aggressive
Most common rib tumor in dogs and accounts for 73% of all rib tumors and is similar to? Do you see rib tumors in cats?
OSTEOSARCOMA (Rib OSA has a similar biologic behavior to appendicular OSA)
(never seen a rib tumor in cats very very rre)
Which is better when working up and staging chest wall tumors thoracic rads/cytology/biopsy/CT? What is the significance of the biopsy and what are we differentiating?
- Thoracic radiographs grossly underestimate extent of local disease but good for screening & met check
• Cytology may give you dx of sarcoma but that is NOT enough
– Need to know subtype of sarcoma (OSA vs. CSA)
• OPEN (wedge) biopsy for tissue dx
– Need large sample (at least > 1cm) bc unique variant called– Chondroblastic OSA makes cartilage = A problem! Because chondrosarcoma comes from cartilage and they may think its that!
– Obtain sample in center of field & minimize hemorrhage
• CT scan needed for surgical planning
How to treat these thoracic chest wall tumors?
Aggressive surgical resection
En bloc excision w/ chest wall reconstruction (Max rib excision = 6)
What are the 4 indications for chest wall reconstruction?
- Cranial to mid-thorax locations = latissimus dorsi muscle flap & external abdominal oblique muscle flap
- Caudal thoracic locations = Diaphragmatic advancement
- Prosthetic mesh augmentation depending on the size & location of the defect
Caudal lung lobectomy may be required to permit adequate closure w/ substantial diaphragmatic advancement (i.e. thoracic cavity diameter is decreased so much that lung is compromised)
Ajunctive ______ is recommended for dogs with rib OSA but genrally not for ____
chemotherapy but not for CSA
Do not need ___ ____ ____ for chest wall tumors BUT need _____ around biopsy tract!
3 cm skin margin; margin
Diaphragmatic reconstruction – Advance _____ & _____ ____ diaphragm to caudal aspect of cut ribs
cranially; suture free
Always place _____ _____ prior to complete reconstruction
thoracostomy tube
Name some of the porgnostic variables for dogs?
- Tumor size = small < 5 cm
- Location= more pripheral is better and easier to excise
- Presence of CS at the time of diagnosis (are they coughing if yes larger and more extnesive tumor which is poor)
- Clinical stage: TBLN or pulmonary metastasis = worse prognosis
- Histiologic score of tumor= vascular lymphatic invasion or higher grade/ worse prognosis
MST is _____ days with OSA following chest wall resection along with chemo
240 days
MST is _____ days with CSA (this is why we…….????)
299-1080 days (this is why we biopsy look at the differenc ein ST)
MST range from _____ - _____days for dogs with FSA
120-450 days
MST range from _____ - _____days for dogs with HSA
30-150 days
Progostic factors for chest wall tumors depend on _____ type and _____ _____ _____. Local tumor reoccurance and metastases is ____x more iliely with incomplete resection wich is why we ____ _____ at surgery.
- tumor
- complete histological resection
- 5.6x
- GO BIG
Lung tumors are ______ in dogs and cats
uncommon <1%
State the difference in signalment and sex predilection for dogs and cats (Compare and contrast)?
Dogs
- Older dogs
- No sex predilection
- Boxer, Doberman, Irish setter, Bernese MD, Aus SHep.
Cats
- Older cat
- FEMALE SEX PREDILECTION
- No breed predisposition (+/- persian)
What are the CS with dogs suffering from Lung tumors?
- Non productive coughing
- Exercise intolerant
- Other resp. signs
- Acute dyspnea/tachypnea if plearal effusion develops
- Smoke exposure???
What are the CS with cats suffering from Lung tumors?
Similar signs as in dogs
Except in 19%
- GI signs (V/D regurg)
- LAMENESS= Lung digit syndrome where it metastesizes to toes on the weight bearning digits and 3rd phalanx******
With lung tumors in cats _____ may be invovled in pathogenesis?
retroviruses
What it the top DDX with lung tumors?
CARCINOMAs
With lung tumors in dogs there tumors are classified as _______ = 97% of primary lung tumors in dogs with _____ _____ more prevalent (85%) and SCC being uncommon. Others= _____ ______ (often ______ pulmonary masses)
- Carcinoma (97%)
- broncoalveolar ACA more prevalent (85%)
- other= histiocytic sarcoma (Multiple)
The most common Lung tumors in cats is ______ _____ (66-71%)
Bronchial ACA
For work up and staging for lung tumors in dogs we generally do _____ because they are demarcated and speherical solitary mass. ______ lobes are more commonly affected. If multiple large masses think _____ or histiocytic disease
- Radiographs
- Caudal
- LSA
For lung tumors in cats there are __ main radiographic presentations which are? ____ lobes most commonl affected
- 3
- Mixed bronchoalveolar
- Ill defined alveolar mass
- Pulmonary mass with cavitation
- Caudal
Compare and contrast thansthroacic FNA/cytology (which is generally performed under u/s guidance with sedation (in dogs and cats) in terms of diagnostics? Careful bc significant bleeding complications possible.
Dogs
- Dx in 38-90%
Cats
- Dx 80-100%
Are pretreat biopsys warranted for dogs and cts with lung tumors?
Gnerally not high risk of commplications
What imaging modality is an essential tool for staging animals with lung tumors
CT
Lung tumors often _____ to the _____ LN
metastesize; tracheobronchial
What is this?
Classic example of primary lung tumor in dog well circumscribed circular and easy to pick out
What is this an example of?
Histiocytic, multilobulated, more than one primary, slightly different appearance
What do we consider in terms of prognosis when we see TB lymph node metastases?
Negative prognosis
What do we never do when we see this on radiographs?
DO NOT EVER EVER EVER amputate a cats digit without FIRST takng CHEST RADIOGRAPHS
What is the main treatment for lung tumors and the approach?
Surgery (lateral thoractomy often 5th intercostal space) for small to medium sized lung tumors with hilar LN biopsy (Even if small on CT) median sternotomy for large tumors
Tool of choice: Thoracoscopic stapler
You need 2 days in hopsital post off bc of thoracostomy tube
Name some of the prognostic variables for dogs? (5)
- Tumor size= < 5 cm
- Location= more peripheral is better (easier to excise)
- Presence of CS at the time of diagnosis (are they coughing if les larger and more extensive tumor) MST 545 days vs 240 days if had CS
- Clinical stage (TBLN or pulmonary metasasis = worse prognosis) MST = T1 (solitary)-26 months, T2 (Multiple)- 7 months, and T3 (invasive into adjacent tissue 3 months. MST 1 month if LN nvolvement versus 15 months
- Histologic score of tuor (vascular / lymphatic invasion or higher grade = worse prognosis) MST 790 days for well dfferentated, 251 days for moderately differentiated and 5 days if poorly differentiated. MST 8months for SCC versus 19 months for ACA
Name some of the prognostic variables for cats? (7) What is most important??
#1. Histological grade is most important
- Poorly differentiated MST 2.5 months
- Well dferentiated MST 23 months
- MST without LN involvement 412 days
- MST with LN involvement 73 days
- MST with metastatic lesions in digits 67 days
- Presence of plural effusion is a negative factor more common in cats
Bernese mountain dogs and _____ are two breeds often see with this type of lung tumor?
Flat coated retriever; Histiocytic Sarcoma
Histiocytic sarcomas are from what origin? Commonly metastastes to? Can be _____ or _____ in terms of distribution? What is the treatment and MST?
Malignant tumors of antigen presenting dendritic cell origin
Commonly to: LN, kidneys, Liver, and CNS
Localized or disseminated
Surgical removal with adjunctive TX wit CCNU**** (MST 568 days)
What is the peak age for Cranial Mediastinal Tumor and the signalment
Dogs- 9 y/o
Cats- 10 y/o
No breed r sex predilection
No known predisposing factos
What are the CS of the Cranial Mediastinal Tumor?
Related to the mass, effect in thorax = lethargy coughing , tachypnea, and dispnea
What kind of syndrome do you commonly see with cranial mediastinal tumors?
Caval syndrome = tumor invasion in Cranial Vena Cava
Edema builds up in head, neck, and forelimbs due to impairment of venous return to right atrium
67% of Thymoma’s are associated with?
Paraneoplastic syndromesuch as:
- Myasthenia gravis (40% of dogs) uncommon in cats (megaesophagus)
- Hypercalcemia of malignancy
What are the top 2 differentials for cranial mediastinal tumors? Which one is most common
1. LSA (most common)
- Thymoma
When doing a transthoracic u/s guided FNA cytology for Thymoma’s describe the unique cytology noted that’s pathognomic for thymoma tumor, what is the most unique cell?
- Neoplastic epithelial cells
- with large #s of small mature lymphocytes
- intermettent mast cells-most unique (85% in dogs, 50% in cats)
Do additonal testing. Send out flow cytometry and look for thymic lymphocytes differentated from peripheral by expression of CD4 and CD8. Only 2% of LSA express CD4 CD8 (NC state or COLORADO)
Which is normal
Right side= normal
Left-no lung tissue, filling effect with mass
Do thymom’as have a predilection to metastesize?
Not commonly!!! so no (more locally infiltrative)
Thymom’as are classified as either _____ or ______
invasive (malignant) versus
- DOGS 50%
non invasive (non malignant)
- Cats 50-100%
How do we figure out if thymoma is invasive?
Exploratory thoracotomy required to definitiely differentiate non invasive and invasive, hopefully pre op 3D CT imaging can gvie you a good feel for itf its non invasive
Invasive thymoma’s will invade adjacent structures such as _____ ____ ____, thoracic wall, and ______. Can we surgically correct these?
Cranial vena cava; pericardium; not usually amenable to surgical resection
What procedure is required due to the size of the thymoma tumor? What about smaller lesions?
Median sternotomy
Intercostal thoracotomy = Smaller lesions or in cats (although adjacent rib
resection sometimes required)
The Non-invasive thymoma’s do not infiltrate into ________ structures and removed using ____ ____ ____ dissection.
_____ ____ _____ & _____ _____ are located along the craniodorsal
aspect of cranial mediastinal mass and Need to be located & spared
intrathoracic; TEDIOUS blunt-sharp; Cranial vena cava; phrenic nerves
If the cranial mediastinal tumor is not amenable by surgery what is our other option?
Radiation Therapy – If not amenable to surgery or as adjunct to surgery (i.e. incompletely excised) 75% response rate in cats and dogs
Describe the effectiveness of chemo with cranial mediastinal tumor?
Chemotherapy
– Usually ineffective, but can be attempted in combination w/ corticosteroids for invasive thymoma
– Isolated case reports of sustained response to high dose steroids (cytotoxic effects on T lymphocytes in tumor) = Try if no other options
If myasthenia gravis is present what can we do with cranial mediastinal tumors?
– Medical management for MG if present = immunosuppressive therapy & anticholinesterase treatment
• Should spontaneously resolve if tumor completely excised at surgery
– Management of megaesophagus if present
Describe the prognosis of thymoma in dogs? Describe the MST with Sx, radiation? What are some poor prognostic factos?
• Sx excision: MST = 790 days
– 1-year survival rate of 64%
– 3-year survival rate of 42%
• Radiation = MST - 248 d
• Poor prognostic factors:
– Age – Younger = WORSE
– Megaesophagus = WORSE if present
– Histologic subtype = Lymphocyte rich variants of tumor lived longer
Describe the prognosis of thymoma in cats? Describe the MST with Sx, radiation? What are some poor prognostic factos?
• Sx excision: MST = 1,825 days
– 1-year survival rate of 89%
– 3-year survival rate of 74%
• Radiation = MST – 720 d
- Myasthenia gravis has been reported in 2 cats PO
- Cystic thymoma variants though to have better PX
What is Myasthesnia gravis and what does it result in? What about the acquired form?
• Causes a deficiency of acetyl choline (ACh) receptors on the postsynaptic membrane
– Results in episodic & profound muscle weakness
• Acquired (immune-mediated) MG
– Antibody mediated destruction of AChreceptors at neuromuscular jxn.
– Pathogenesis is poorly understood…
– Due to the striated musculature in the canine esophagus and megaesophagus is present in ~ 85% of canine cases of MG
