Some dogs present with non-specific clinical signs such as lethargy, anorexia, vomiting and weight loss. The most common clinical signs at presentation is a haemoabdomen and distended abdomen, secondary to a bleeding splenic mass (clinical substage b). There is no apparent gender or breed predilection. Middle-aged to older dogs are primarily affected (mean age 8 to 10 years). It is characterised by abnormal proliferation of small mature lymphocytes in the marginal zone of lymphoid follicles, in the spleen (stage IV) and generally, has a relatively slow clinical course of disease. Splenic marginal zone lymphoma is a form of indolent B-cell lymphoma representing between 4 and 36% of canine indolent lymphoma. Also, when dogs go into complete remission from therapy, other associated infections (such as demodicosis) typically resolves. 1 Although this is numerically different, treatment type was not found to be significantly different statistically. The median survival times for canine indolent lymphomas treated with chlorambucil and prednisolone exceed 44 months, compared to 22 months in dogs receiving a CHOP based chemotherapy protocol. Despite not attaining complete remission, dogs can still live a long time. Although a complete remission is ideal and may occur in dogs with TZL, it is unusual in dogs with indolent lymphoma. With this approach, the goal of therapy is to control the disease (i.e. When therapy is deemed necessary, the treatment of choice for canine TZL is chlorambucil and prednisolone. However, it is best not to start treatment as long as the dog feels well.
This will entail regular monitoring of complete blood counts (including blood film review), and physical examination is recommended, initially monthly for three months, and if stable, then every two to three months thereafter. In asymptomatic dogs with stable lymphadenopathy and/or lymphocytosis and no cytopaenias, ‘active surveillance’ is recommended. Peripheral cytopaenias are uncommon (9K cells/μL have median survival times of 15.4 months compared to not reached if lymphocyte counts 9K cells/μL, or massive or progressive lymphadenopathy or hepatosplenomegaly. The most common abnormal clinicopathologic finding is lymphocytosis (50-65%), and it is typically mild (median 5-6K cells/μL, range 1K to 31K cells/μL). 8 These are speculated to occur due to immune dysfunction from the indolent lymphoma. 70% of dogs present with concurrent medical problems such as adult-onset of demodicosis (10- 50% of dogs), infection or other neoplastic diseases.
6 Dogs can also present with splenomegaly and/or hepatomegaly. TZL is classified as stage V in 93% of cases due to peripheral blood and/or bone marrow involvement. 5 If clinical signs are present, it is usually non-specific and mild.
5 There is no apparent gender predilection.ĭogs typically present with generalised peripheral lymphadenopathy (that may wax and wane) and/or lymphocytosis with no clinical signs of illness (clinical substage a, 80%). Middle-aged to older dogs are primarily affected (median age 8 to 10 years).5 Common breeds affected include Golden retriever (40-50%) 6,7 and Shih Tzu. 4-6 This subtype is associated with the longest median survival times in dogs with indolent lymphoma. 1 TZL is characterised by unique loss of CD45 expression, T-zone distinct histologic pattern and small clear cell cytomorphology. T-zone lymphoma is the most common subtype in canine indolent lymphoma representing around 60% of dogs with indolent lymphoma. Some dogs present with solitary lymph node involvement or only splenic involvement.įew dogs present with clinical signs, and if clinical signs are present (including lymphadenopathy), it can wax and wane and is usually mild. Most dogs with indolent lymphoma present with generalised lymphadenopathy. In general, indolent lymphoma is characterised by small lymphocytes, a low mitotic index and slow clinical course of progression. The subtypes described include follicular lymphoma, marginal zone lymphoma, mantle zone and T-zone lymphoma, which are all derived from B-cells (except for T-zone lymphoma, which is T-cell in origin). Indolent lymphoma (also called small-cell or low-grade lymphoma) is an uncommon form of lymphoma in dogs, representing around 5-29% 1 of all canine lymphoma. What is indolent lymphoma? What is the prognosis and what are the treatment options?