LRT Neoplasia in SA

Question 1

How are tumours sub-classified?

Answer 1

• By tissue of origin
• Then by benign vs malignant
• But remember, when talking to clients, they won’t know what a tumour is – tell them if it is cancerous or not!

Question 2

Explain Lymphoma

Answer 2

• Lymphoma = lymphosarcoma = malignant
• Subclassified histologically by:
  
  • cell type
  • grade (cellular differentiation, mitotic rate etc)
  • Cell distribution (diffuse/ nodular)
• Also immunophenotyping and anatomic site
  
  • B vs T – very simplistic
  • Multicentric, alimentary, thymic, cutaneous, extranodal
• Remember paraneoplastic problems
  
  • Chemo and radiation sensitive
    
    • Rarely considered a surgical disease

Question 3

Explain Leukaemia

Answer 3

• Leukaemia = any bone marrow derived haematopoetic neoplasm
  
  • Lymphoid vs myeloid (anything NOT a lymphocyte) cell lines in origin
    
    • Rarely see erythroleukaemias
  • Acute (AML/ ALL) vs chronic leukaemia (CLL/CML)
  • Chronic > acute chemosensitivity
• Multiple myeloma = plasma cells
  
  • Secrete excess Igs of one clonal class
  • Usually present due to paraneoplastic signs
  • Chemosensitive
• MDS = myelodysplastic syndromes
  
  • Pre-malignant in some variants

Question 4

Characteristics of benign vs. malignant tumours

• Growth rate
• Growth manner
• Effects on adjacent structures
• Mets
• Effect on host

Answer 4

Benign

• Growth rate: relatively slow
• Growth manner: Expansive
• Effects on adjacent structures: Often minimal pressure necrosis and deformity
• Mets: doesnt occur
• Effect on host: often minimal. though serious if develops in brain or obstructs GIT.

Malignant

• Growth rate: often fast
• Growth manner: invasive
• Effects on adjacent structures: invades and destroys
• Mets: present via lymphatics, haematogenous and transcoelomic spread
• Effect on host: often life threatening

Question 5

Where can tumours arise?

Answer 5

• Nasal planum
• Nasal cavity
• Tonsils, larynx, pharynx, trachea
• Mediastinum
• Thyroid
• Thymus
• Heart and great vessels (see RJ lectures)
• Lung parenchyma
• Pleura
• Ribs

Bold = can see them, otherwise, quite challenging

Question 6

What clinical signs might you see with tumours located in:

• Nasal
• upper airways
• Lower airways and pulmonary
• Mediastinal
• Pleural
• Cardiac

Answer 6

• Nasal
  
  • Discharge (blood)
  • Nasal sturtor
• upper airways
  
  • larynx and trachea
    
    • Changes in vocation
    • Resp. stridor
• Lower airways and pulmonary
  
  • Dyspnoea (but with pulmonary parenchyma it is much less likely)
  • Chronic weight loss
  • lethargy
• Mediastinal
  
  • Dyspnoea
  • Cranial mediastinal area often very dull
• Pleural
  
  • Similar to mediastinal, but often diffuse, so loss of lung sounds
  • Increased resp inspiratory and expiratory effort
• Cardiac
  
  • Not much - may present collapsed, arrhythmiasa, oedema etc.

Question 7

Nasal planum neoplasia

Answer 7

• White cats with solar exposure, rare in dogs
• Carcinoma in situ àsuperficial SqCC àinfiltrative SqCC, locally invasive, mets rare.
• Locally problematic, but rarely mets. Also seen on the pinna.
• Therapies: Photodynamic therapy (PDT), planectomy (biopsy may cure!), immunomodulators (imiquimod)
• Good prognosis with nose off, may need repeat PDT

Question 8

Nasal cavity disease investigation methods

pros and cons of:

• Radiography
• MRI
• CT
• Rhinoscopy

Answer 8

Radiography

Pros

• Relatively cheap
• Readily available
• Quick to perform

Cons

• Superimposition – will have to be intra-oral film, poor resolution.

MRI

Pros

• Gold standard for soft tissue

Cons

• Expensive
• Long time
• GA required

CT

Pros

• Gold standard for bony involvement
• Cheaper than CT, more accessible.
• Quicker to perform cf. MRI – which will need an anaesthetic cf. sedation for CT.

Cons

• No good for soft tissue

Rhinoscopy

Pros

• Can see something and biopsy at same time – targeted samples.
• Can see mucosa

Cons

• Invasive
• Traumatic
• Structure of nose – not empty, full of turbulent bones, so difficult to see easily. So sensitivity is very poor – cannot tell you nothing is there, but specificity is good – if you see something abnormal, can take a biopsy and get a diagnosis.

Question 9

Nasal cavity tumours

Answer 9

• 3% of all neoplasms dogs and cats are nasal tumours.
• Dogs: carcinomas, rarely SqCC, lymphoma, fibrosarcomas, chondrosarcomas and osteosarcomas
• Cats: adenocarcinoma or lymphoma > others
• Investigation: MRI/ CT (usually CT) then rhinoscope and biopsy
  
  • If see a lump on CT, measure it, plan where the lump is and measure where biopsy needs to get to without needing rhinoscopy.
• Therapy: radiotherapy+/-chemo +/NSAIDs
• Little apparent benefit of surgical resection
  
  • Margins and morbidity
  • Exceptions?
• Guarded prognosis (dog carcinomas approx 250 days MST with radiotherapy or NSAIDs)

Question 10

Larynx and trachea tumours (URT)

Answer 10

• RARE
• Cats: laryngeal lymphoma recognised, very similar granulomatous proliferation
• Dogs: oncocytoma/rhabdomyosarcoma, tracheal cartilaginous tumours, OSA, fibrosarcoma, SCC
• Usually diagnosed on examination under anaesthesia, then biopsy if possible
  
  • Animals that have changes in resp noise, might not be apparent during normal PE until GA.
• Tracheal masses may be benign so can be resected, difficult surgery - refer
• Need for permanent tracheostomy rare but may be required.

Question 11

Pulmonary parenchyma neoplasias (cancer of the lung)

Answer 11

• Primary lung tumours are very rare in comparison to humans (1%)
• Dog>cat, weak links with passive smoking
• Metastatic disease by far the commonest
  
  • Oral melanoma, thyroid Ca, osteosarcoma, haemangiosarcoma and mammary Ca.

Question 12

Primary lung cancer

Answer 12

• Median age 11 years
• Generally carcinomas, classified by location, often hard to tell exact origin
  
  • Can also see pulmonary lymphoma, pulmonary lymphomatoid granulomatosis, malignant histiocytosis
  • Rare to see mesenchymal tumours in the lung
• >50% solitary (often right caudal lobe)
• Present with non productive cough or exercise intolerance
• Long standing low grade cough.
• Hypertrophic osteopathy as rare paraneoplastic disease
• Often lose weight.

Question 13

Metastatic disease and therapy

Answer 13

• May be incidental finding or present with cough/ tachypnoea
• May be the first an owner knows about animal having cancer
• Commonest = osteosarcoma, haemangiosarcoma, thyroid carcinoma, melanoma of the mucocutaneous junction
  
  • check pre-op!
  • Remember not all tumours met to the chest
• Interesting but no great merit in finding 1◦ if no plans to treat
• Emphasis on finding mets?

Met therapy

• Solitary metastasis removal increasingly common
  
  • Need CT to get best info on how many and where, and slow radiographic doubling time
  • Thoracoscopic approaches increasing
  • Care on seeding to portal sites
• May start getting locally delivered chemo
  
  • Delivery and penetration problems
• Median survival time 3 months with no tx
  
  • Unclear survival if early detection on CT

Question 14

Mediastinal disease overview

Answer 14

• May be benign or malignant tumours, cystic lesions, enlarged mediastinal lymph nodes or haematomas
• Pros and cons of diagnostic imaging as for lung masses though CT very useful if surgical
• May be hidden behind pleural effusion – check tracheal position
• Diagnosis can be very challenging however important as clear distinction in treatment options for e.g. lymphoma vs sarcoma
  
  • Surgery not indicated for lymphoma.

Question 15

Mediastinal lymphoma

Answer 15

• Commonest in young cats (predisposition for siamese?), also seen in dogs with multicentric or stage 3-5 lymphoma if so is considered a negative prognostic indicator
• Tachypnoea, inspiratory hyperpnoea, dull heart sounds, pleural effusion (cytology for dx)
• Non compressible anterior mediastinum
  
  • NB practice compressing normal
  • Check compressibility of the cranial chest – if mass there, you cannot compress the chest.
• Check FeLV/ FIV status (~50% positive for FeLV)
• DDx thymoma – consult a cytologist!
  
  • Thymoma is surgical
• Treatment: chemo +/- radiotherapy?
• Generally remission, cure rare

Question 16

Thymoma

Answer 16

• RARE, commonest in older dogs, very rare in cat’s.
• From thymic epithelium, often infiltrated with lymphocytes
  
  • Ddx thymic lymphoma – good cytologist!
  • Challening to diagnosis because of lymphocytes.
• Benign or malignant, mets rare from both
• 60% feline version cystic
• Present with resp distress +/- cranial caval syndrome +/- myaesthenia gravis
• Megaoesophagus also common if focal MG or disrupted due to presence of mass

Question 17

Thymoma diagnosis and treatment

Answer 17

• Thoracic radiographs to confirm a mass
• Cytology +/- tru-cut +/- flow cytometry to get diagnosis
  
  • Be sure of diagnosis as possible - lymphoma is not a surgical disease
  • Adjunctive imaging eg CT may help
• Surgical resection as treatment of choice – excellent prognosis if fully resectable
• Poor prognosis if old, megaoesophagus, invasive

Question 18

Pleural tumours

Answer 18

• Mesothelioma - RARE
• From epithelial lining cells – pleural, abdominal, pericardial
• Major link with asbestos inhalation, complex mechanism
• Causes large volume effusions and pain ++
• Multifocal small masses, hard to image, Ultrasound and CT most useful.

Question 19

Mesothelioma diagnosis

Answer 19

• Diagnosis hard, ddx reactive mesothelial cells if fluid been there for a long time.
• Histo ideal, thorascopy histology best as non-invasive.
• Treatment via intra-cavitary carboplatin/ cisplatin, but painful and poor prognosis.
• Large volume effusion cause of euthanasia

Question 20

Rib tumours

Answer 20

• The iceberg tumour!
• Osteosarcomas and chondrosarcomas, but remember overlying soft tissue tumours too e.g. infiltrative lipomas
• OSAs aggressive in this location (cf other axials)
• What is visible on the outside may be only 20-30% of the total
• Treatment via rib resection = thoracotomy plus post-op chemo if osteosarcoma
• Prognosis depends on diagnosis – chondrosarcoma better than osteosarc