Page 1297 - Clinical Small Animal Internal Medicine

134 Lymphomas 1235

chemotherapy agents/protocols. Successful induction of Cutaneous Lymphoma
VetBooks.ir an additional remission with rescue protocols varies within the skin and/or the oral cavity (mucocutaneous).
A primary cutaneous form of lymphoma can develop
between 50% and 90% but the length of remission is
Dogs may present with pruritus, scaling of the skin, and
decreased, at 1.5–2.5 months.
A novel chemotherapy agent, rabacfosadine (Tanovea®), alopecia that will progress to areas of ulceration, nod­
has been conditionally approved for use in dogs with naive ules, and proliferative plaques. Lesions can be solitary or
or relapse lymphoma. This compound as a single agent has can involve multiple skin sites. Oral involvement appears
demonstrated excellent efficacy for dogs with B cell form as plaque‐like lesions or nodules associated with the
of lymphoma and may be variably successsful for dogs gums and lips. Multiple punch biopsies of the affected
with a T cell variant. Other second‐line drugs often used areas are necessary to establish a diagnosis of lymphoma.
for rescue therapy include lomustine (CCNU), mechlore­ There are two types of cutaneous lymphoma distin­
thamine (Mustargen®), vinblastine (Velban®), dacarbazine guished histologically and phenotypically: epithelio­
(DTIC), and cytosine arabinoside (Cytosar‐U®). While tropic (T cell) lymphoma (also called mycosis fungoides)
each of these drugs has a variable degree of efficacy against and nonepitheliotropic (B or T cell) lymphoma.
lymphoma, the duration of response is considerably lower Treatment of cutaneous lymphoma depends on the
when compared to standard multiagent protocols. extent and location of disease. Single lesions may be
appropriately treated with local therapy consisting of
Complications of Chemotherapy surgery or radiation therapy. Diffuse cutaneous lym­
A majority of dogs tolerate chemotherapy well. Potential phoma is best treated with chemotherapy. B cell cutane­
adverse effects include mild to moderate nausea, vomit­ ous lymphomas often respond better than T cell, but the
ing, or diarrhea, all of which are easily treated with sup­ response rate with chemotherapy is less than that seen
portive care or symptom management. In rare instances, with other forms of lymphoma.
life‐threatening complications related to chemotherapy‐ CCNU or multiagent chemotherapy is the treatment
induced myelosuppression can develop, requiring hospi­ of choice, although a recent study has also supported the
talization and aggressive supportive care. use of Tanovea when treating dogs for cutaneous forms
A CBC must be performed prior to every treatment to of lymphoma. While many dogs have an initial response
ensure an adequate white blood cell count. It is generally to chemotherapy, the lesions often return or new lesions
accepted that an absolute neutrophil count of >2000 develop within a short period of time (3–5 months).
cells/μL and >50 000 platelets/μL be present prior to Many dogs are euthanized within six months of diagno­
chemotherapy administration to minimize the risk of sis due to the discomfort associated with progressive
sepsis or other complications. ulceration, bleeding, and pruritus.

Extranodal Forms of Lymphoma Prognosis
There are instances where a dog will present with lym­ Response rates and remission duration for dogs with
phoma isolated to a solitary site, such as the alimentary newly diagnosed lymphoma will vary depending on the
tract, skin, central nervous system (CNS) or nasal cavity. clinical picture, biologic behavior, histologic classifica­
On rare occasions, local therapies such as surgery or tion, immunophenotype, and treatment protocol. In
radiation therapy may be employed. Careful staging, general, dogs with large B cell lymphoma have better
including bloodwork, thoracic radiographs, +/‐ abdomi­ response rates to a CHOP‐based chemotherapy protocol
nal ultrasound, +/‐ bone marrow aspiration, is essential than dogs with T cell lymphoma. In fact, due to the vari­
to ensure multicentric involvement is not present before able success in the treatment of dogs with T cell lym­
considering local therapy. phoma, many oncologists are now relying on a modified
chemotherapy protocol that incorporates more alkylat­
Alimentary Lymphoma ing agents (e.g., cyclophosphamide or lomustine). This
Alimentary lymphoma is an uncommon extranodal lym­ modification is based on the presumption that these
phoma. Dogs will present with nonspecific clinical signs agents may be more effective agents for dogs with a T cell
consistent with gastrointestinal (GI) disease, including form of lymphoma.
weight loss, anorexia, diarrhea, and vomiting. Limited
information in the veterinary literature suggests this Additional Treatment Strategies
form of lymphoma is poorly responsive to chemother­ Because most dogs ultimately will develop chemother­
apy. In the author’s experience, a chemotherapy protocol apy resistance, other methods of lengthening a clinical
that incorporates CCNU can be more effective than a remission may be employed. These include total and
multidrug CHOP‐based chemotherapy protocol alone. half‐body radiation therapy, hematopoietic stem cell