Canine Lymphoma Flashcards
describe lymphoma
- malignant cell (lymphocyte) originates from lymphoreticular cells
-lymph nodes!!
-spleen
-bone marrow
-GALT
-skin - systemic disease
describe canine lymphoma classification
- histologic grade/size of cells
-grade based on mitotic count (MC)/hpf (400x)
-low: 0-5/hpf
-intermed: 6-10/hpf
-high: >10/hpf, most common, rapidly dividing - immunophenotype, B or T cell:
-diffuse large cell B cell lymphoma (DLCBL) most common - anatomic form:
-multicentric form most common - stage/substage:
-stage 3-5 most common
which peripheral LNs should you always be able to feel? which are only palpable if normal?
always able to feel: mandibular, prescapular, popliteal
only palpable if abnormal: axillary, inguinal
describe the clinical signs of lymphoma
“happy dog with lumps”- huge lymph nodes
+/- hepatosplenomegaly
+/- PU/PD
+/- uveitis
+/- GI signs
+/- respiratory signs
describe the first step when you see an enlarged lymph node?
fine needle aspirate!
diagnostic slide: broken cells = NON diagnostic!!
can likely just aspirate one lymph node; if lymphoma is in one, probs in others
preference for prescap or popliteal, try to avoid mandibular (plasma cells already in there could lead to false diagnosis)
describe lymph node cytology results
- normal:
-90-90% mature lymphocytes
-5-10% lymphoblasts, other - lymphoma:
- >50-90% lymphoblasts
-use neutrophil as micrometer for size - reactive:
-up to 50% lymphoblasts
-small lymphocytes
-plasma cells
-neutrophils, eosinophils, etc.
once you make the diagnosis of lymphoma, what do you tell the owner about the diagnosis?
- common cancer, esp in some breeds
-golden retrievers, boxers - systemic disease, so chemotherapy is treatment of choice
- treatable, but rarely curable (MST approx 1 year)
-similar to non-Hodgkin’s lymphoma in people
describe clinical staging of lymphoma
- cytology or excisional biopsy of affected lymph node
-if only do one thing, do this; cytologic diagnosis sufficient to allow you to being treatment! - CBC, chem panel, UA: perform min database because relatively inexpensive, and can help start to plan treatment protocol
- thoracic rads: most common imaging (can’t palpate much in thorax)
- abdominal imaging: to confirm hepato or splenomegaly
- bone marrow aspirate
- immunophenotyping
I: involvement of a single node
II: involvement of multiple nodes in a regional area (ex. one side of the diaphragm)
III: generalized lymph node involvement
IV: liver and/or spleen involvement
V: blood and/or bone marrow involvement OR extra nodal sites
substage a: without systemic signs (not sick)
substage b: with systemic signs (sick)
describe what might be seen on a CBC, chem, UA of lymphoma
often normal (common with many cancers), but could see
- anemia
- leukocytosis/stress leukogram
- thrombocytopenia
- pancytopenia
- HYPERCALCEMIA
- increased liver enzymes
- monoclonal gammopathy
describe what might be seen on thoracic rads of lymphoma
- lymphadenopathy
- diffuse interstitial pattern
- rarely nodular pattern
describe why would perform bone marrow aspirate of lymphoma
needed to completely stage, very rarely done though, if bone marrow injured enough will pick up on CBC too
describe immunophenotyping
- the most important prognostic factor!!
-B is better, T is tougher - ID of lymphoid lineage
- T cell versus B cell
-immunohistochemical staining of tissue samples
-immunocytochemical staining of air-dried cytology slides
-flow cytometry
-commercially available
-T cell marker: CD3, CD4, CD8 (FYI)
-B cell marker: CD79a, CD20, CD21 (FYI)
describe lymphoma treatment generally
- chemotherapy: lots of options
-consider side effects (if true hair, will lose, hair color change, etc.)
-multi drug protocols preferred
-potentially maybe prednisone alone if budget and time constraints - define your goal:
-clinical remission: resolution of clinical signs - why don’t we cure them?
-multi-drug resistance; utilize different drugs with different mechanisms in different cycles
-cause of treatment failure
-numerous mechanisms (P-glycoprotein pumps drug out) - rescue chemotherapy:
-lots of options, just don’t work super great
describe remission of lymphoma
- most are responsive to chemo, some will go into remission with pred alone
- how know if treatment working?/how define remission?
-resolution of clinical signs
-decrease in LN size
-normalization of calcium - sometimes works within days of first treatment
- but conclude that treatment is NOT working after treatment with doxorubicin or after all drugs in protocol have been tried
describe lymphoma prognosis
MST for multicentric LSA
- combination chemotherapy including adriamycin: approx 1 year (B cell > T cell)
- single agent adriamycin: 6-9 months
- pred alone: 2-3 months
- no treatment: 4-6 weeks
