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prognostic factors and therefore immunophenotyping is always recommended. IHC is considered the
gold standard, however collection of biopsies
solely for purposes of IHC in a dog with previously diagnosed lymphoma may be difficult to justify from the standpoint of invasiveness and cost, when less invasive options exist. In my opinion, flow cytometry would be considered the next preferred option, followed by immunocytochemistry and then PARR because of the limitations already discussed in turnaround time and sensitivity.
Canine lymphoma classification:
· Subtype: The WHO classification scheme is based on tissue architecture, cell size, mitotic rate, cellular features and immunophenotype. There are approximately 40 different subtypes. Pathologist expertise is important when classifying lymphoma and there is good,
chemotherapy protocol for high grade/large cell lymphoma)
· Epitheliotropic T cell lymphoma
· Cutaneous: Most are diffuse and respond well initially to chemotherapy but progress within
a few months. Alternative treatments such as isotretinoin or safflower oil may help in some cases. Solitary lesions may be associated with a better prognosis (Chan)
· Oral/mucocutaneous: If lesions are localised to the oral cavity then outcomes with chemotherapy or radiation therapy can be very good (> 1-2 years), and again solitary lesions may be associated with better prognosis (6, 7)
Summary:
Canine lymphoma encompasses a group of diseases with varying clinical presentations, need for diagnostic tests, treatment options and prognosis. In my clinical practice, to treat a dog with lymphoma, the things I need to know are:
but not perfect agreement between pathologists (approximately 90% when only the 6 most common types are considered). From a practical standpoint, the important considerations are: identifying B versus T cell in large cell lymphoma, identifying T zone lymphoma separately from other T cell lymphomas, and identifying low grade B cell lymphomas, especially splenic marginal zone lymphoma. As well as considering the WHO subtype, clinical progression must be considered. T zone lymphoma, marginal zone lymphoma, mantle
· Subtype as much as is reasonable i.e. large cell/small cell, immunophenotype and clinical behaviour at a minimum. Flow cytometry is my preferred option for immunophenotyping following a cytological diagnosis as it also enables diagnosis of T zone lymphoma. If a diagnosis has been made on histopathology, IHC is preferred for immunophenotyping
cell lymphoma and follicular lymphoma are generally considered indolent in behaviour. They often present as peripheral lymphadenomegaly (+/- lymphocytosis) which is slowly progressive. Although they are generally poorly responsive to standard maximum tolerated
· Minimum database of CBC/serum chemistry/urinalysis
· Substage - assigned based on systemic signs
· In a dog with a confirmed diagnosis of multicentric
dose chemotherapy, prolonged survivals are common. Treatment is often not initiated at the time of diagnosis unless there are clinical signs or evidence of more rapid or advanced clinical progression. When treated, the most common initial protocol is chlorambucil and prednisolone. Within these ‘indolent’ subtypes, those of B cell origin generally do not have as good a prognosis as T zone lymphoma. There are some cases where
lymphoma, additional diagnostic tests are not uniformly recommended in order to assign the case to stages I-V, unless it is felt that prognosis or treatment options would be changed by the result of these tests.
an indolent lymphoma can undergo transformation
to acquire more malignant behaviour and rapid progression. These are generally associated with a poor outcome, and reinforce the need to consider the clinical behaviour as well as the subtype.
References:
Vail DM, Withrow SJ, editors. Withrow and McEwen’s Small Animal Clinical Oncology (5th edition) W.B. Saunders, Philadelphia, 2012 is recommended as a general resource
1. Graff EC, Spangler EA, Smith A, Denhere M, Brauss M. Hematologic findings predictive of bone marrow disease in dogs with multi-centric large-cell lymphoma Vet Clin Pathol 2014;43:505-512
2. Martini V, Melzi E, Comazzi S, Gelain ME Peripheral blood abnormalities and bone marrow infiltration in canine large B-cell lymphoma: is there a link? Vet Comp Oncol 2015;13:117-123
3. Prudic RA, Saba CF, Lourenco BN, Bugbee AC. Prevalence of proteinuria in a canine oncology population J Small Anim Pract 2018. DOI: 10.1111/jsap.12840 Epub ahead of print.
4. Di Bella A, Maurella C, Cauvin A, Schmidt JM, Tapia BB, North SM. Proteinuria in canine patients with lymphoma J Small Anim Pract 2013;54:28-32.
5. Van den Steen N, Berlato D, Polton G, Dobson J, Stewart J, Maglennon G, Hayes AM, Murphy S. Rectal lymphoma in 11 dogs - a retrospective study J Small Animal Pract 2012;53:586-591
6. Berlato D, Schrempp D, Van den Steen N, Murphy S. Radiotherapy in the management of localised mucocutaneous oral lymphoma in dogs: 14 cases. Vet Compar Oncol 2012;10:16-23
7. Chan CM, Frimberger AE, Moore AS. Clinical outcome and prognosis of dogs with histopathological features consistent with epitheliotropic lymphoma: a retrospective study of 148 cases (2003-2015) in Australia. Vet Dermatol 2017 DOI: 10.1111/vde.12504 Epub ahead of print
· Anatomic location is also part of WHO classification, but some specific sites bear separate consideration
· Hepatosplenic and primary hepatic - generally aggressive and associated with lower likelihood of response to chemotherapy
· Splenic - often marginal zone and can do quite well with splenectomy alone, however case selection is important - i.e. confined to spleen, not large B cell lymphoma
· Rectal - mostly B cell and tend to have a good prognosis with chemotherapy based on the small numbers of dogs published in the literature (5)
· Gastrointestinal - High grade/large cell GI lymphoma in dogs is generally associated with a poor outcome. Recently, low-grade/small cell GI lymphoma has been recognised and seems to behave like the more common low-grade/small cell GI lymphoma
in cats. Outcomes tend to be much better and recommended treatment is different (oral chlorambucil and prednisolone versus multi-agent CHOP or other
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