Lymphoma Flashcards
Compare the px for high grade B and T cell lymphomas
When treated with CHOP‐based protocols, dogs with high‐grade T cell lymphoma (TCL) have a lower remission rate, and those that do achieve a remission are reported to relapse more quickly and survive a shorter time than dogs with comparable stage high‐grade, B cell lymphoma (BCL)
However, the prognosis for dogs with a separate entity of indolent TCL is mostly considerably better than for dogs with any other type of lymphoma
How can you identify T cell lineage
CD3
PARR
Some neoplastic T cells lose the CD3 antigen but retain the TCR, hence some TCL may be negative for CD3 but positive on PARR
Are most lymphomas B or T cell in dogs?
Mostly B cell, although certain breeds are more commonly T cell (e.g. Sharpei, CKCS)
Which type of lymphoma in dogs is more likely to cause hypercalcaemia
Dogs with TCL appear more likely to present with hypercalcaemia, which appears to be mediated primarily by upregulation of parathyroid hormone related protein (PTHrP
What are the major types of t cell lymphoma?
T zone lymphoma (TZL) and high‐grade TCL
What is T zone lymphoma?
characterised by an expanding paracortical population of T cells that compress the germinal centres causing atrophy throughout the medulla. Morphology of the neoplastic cells is small to intermediate with absent to rare mitoses
difficult diagnosis to make on cytology, as the histological characteristics are more important than cell size
When do you treat T zone lymphoma?
Often don’t need to start straight away
There is no consensus as to criteria to use to institute therapy in dogs with TZL. The presence of the following are suggested as reasons to start therapy:
▪ Clinical signs (substage b);
▪ Rapid progression (doubling time of <6 months);
▪ Circulating lymphocyte count >9.2;
▪ Bulky multiple sites >3 cm or one site >7 cm;
▪ Development of myelosuppression due to myelophthisis; or
▪ Organ dysfunction due to infiltration
What are some suggested aetiologies of lymphoma?
Genetic and epigenetic changes and congenital
aberrations
Possible infectious causes unproven as yet in dogs
Environmental factors
Chemical exposure, polluted sites, incinerators and
radioactive waste
Immune system alterations
Many cases have recent inflammatory event
Prior immune mediated disease associated with a
higher risk of subsequent lymphoma
What are the main presentations of lymphoma?
Multicentric 80% Increasingly being subclassified Craniomediastinal 5% Gastro-intestinal 5 – 7% Cutaneous Extra-nodal forms
How does multicentric lymphoma present?
Usually aggressive disease Occasional indolent cases Typical presentation Well dog to mild lethargy, weight loss, inappetance, pyrexia Rapid progression Ocular changes common Big lymph nodes Around 20% pu/pd due to hypercalcaemia
How does cranio-mediastinal lymphoma present?
Can occur as solitary lesion or part of multicentric form
Malaise
Often pu/pd due to hypercalcaemia
Possibly tachypnoea, dyspnoea
Occasionally pre-caval syndrome
Altered position of PMI for cardiac auscultation
How does the gastrointestinal form present?
Tends to be aggressive in dogs
Diagnosis often delayed due to investigation in to GI signs
There may be progression from other GI disease
Clinical signs
Weight loss, anorexia, pan-hypoproteinaemia, evidence of malabsorption
Abdominal masses
Occasionally multicentric lymphadenopathy
How does cutaneous lymphoma present?
Epitheliotrophic and non-epitheliotrophic forms
Epitheliotrophic T cell solitary or generalised may have lesions elsewhere GI tract and local lymph nodes
Non-epitheliotrophic
More frequently B cell
More likely to have lesions elsewhere
What extranodal forms are there?
Hepatosplenic - Aggressive, no peripheral lymphadenopathy T cell Intravascular Ocular signs CNS Bone marrow Renal Rectal lymphoma
What paraneoplastic forms are common with lymphoma?
Hypercalcaemia T cell Immune mediated diseases IMHA IMTP and Pemphigus IMHA, IMTP and Pemphigus foliaceous Monoclonal gammopathies Neuropathies Cachexia
