Page 745 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 33 Hematopoietic Tumors 723

and obstructive lesions. 439,488,496 Of current debate is whether
surgery should be performed on discrete lesions that are not per-
forated or obstructed before initiating systemic chemotherapy.
VetBooks.ir This question is currently unanswered as comparative trials have
not clearly established a benefit or detriment to this approach.
The motivation behind performing surgery before chemotherapy
often lies with concern for GI perforation resulting from robust
chemotherapy response in cases with full-thickness involvement
with lymphoma. Crouse reported on 23 cats with discrete I/
HGAL undergoing chemotherapy without surgery. Although four
cats (17%) experienced perforation, these events occurred 2 to
87 days after initiation of chemotherapy rather than in the acute
postchemotherapy period, they were not associated with size or
degree of hypoalbuminemia, and progressive disease was docu-
mented in three cats and only a partial response in the other cat at
the time of perforation. 437 Taken together, this implies that per-
forations were likely due to progressive disease rather than robust
response to chemotherapy. An additional motivation for surgical
intervention is the theoretical advantage of immediate creation of • Fig. 33.14 A cat presented with mandibular lymphadenopathy that was
a “minimal residual disease” state if staging does not reveal disease confirmed to be Hodgkin’s-like lymphoma after histologic assessment.
distant from a large GI primary tumor; chemotherapy is generally
thought to result in more favorable outcomes in the minimal dis-
ease state, rather than in the macroscopic disease state. The author In contrast, approximately one-quarter of all other anatomic
generally recommends surgery, albeit in the absence of convincing forms of lymphoma have some component of lymph node
support in the literature, if lesions are large, discrete, and no (or involvement. One-third of cats with nodal lymphoma are T-cell
minimal) involvement is documented outside the primary mass immunophenotype and FeLV antigenemic; however, complete
after complete staging. Multiagent chemotherapy is then initiated categorizations have not occurred in the post-FeLV era and this
at suture removal owing to the high-grade nature and overall short may no longer be true. 427,428,435,492 Peripheral nodal lymphoma
STs associated with I/HGAL. was the most common anatomic form of lymphoma reported
in a compilation of cases in cats under the age of 1 year, rep-
The Role of Radiation Therapy in Cats with resenting one-third of cases in this age group. 433 As lymphoma
Gastrointestinal Lymphoma progresses, bone marrow and hepatic infiltration may develop.
Radiation therapy (RT) for GI lymphoma in cats has not been Clinical staging and diagnostic approach for peripheral lymph-
thoroughly explored and is generally reserved for consolidation adenopathy and peripheral nodal lymphoma is similar to the dog
therapy (during or after chemotherapy) or as a rescue modal- (see Section A of this chapter).
ity. 538,539 In one report, 11 cats (six small cell, four large cell, and Cats with the nodal form of lymphoma present with variable
one LGL) that progressed after chemotherapy received abdominal clinical signs depending on the extent of disease; however, they are
radiation (8 Gy in two fractions over 2 days) and experienced a often depressed and lethargic. Peripheral lymphadenopathy, as the
MST of 7 months, although numbers were small and 40% were only physical finding, is an uncommon presentation.
lost to follow-up. 538 In a second report, eight cats (seven with I/ An uncommon and distinct form of nodal lymphoma in cats
HGAL) underwent 6 weeks of CHOP-based combination che- referred to as “Hodgkin’s-like” lymphoma has been reported. 541,542
motherapy followed 2 weeks later by whole abdomen radiation This form typically involves solitary or regional lymph nodes of
consisting of 10 daily 1.5 Gy fractions. 539,540 Although three cats the head and neck (Fig. 33.14) and histologically resembles Hodg-
died within 3 weeks of RT, five experienced durable remissions. kin’s lymphoma in humans. Affected cats generally present with
These preliminary results warrant further investigation before RT enlargement of one or two mandibular or cervical nodes initially,
can be recommended as standard care. and tumors are immunophenotypically classified as T-cell–rich,
B-cell lymphoma. Histologically, lymph nodes can be effaced by
Supportive Care for Cats with Gastrointestinal either nodular or diffuse small to large lymphocytes with char-
Lymphoma acteristic bizarre or multinucleated cells (Reed–Sternberg-like
Intuitively, GI disease may compromise the nutritional status of cells) (Fig. 33.15). No association with FeLV or FIV has been
affected cats. As such, careful and repeated assessments of nutri- documented. Cats with Hodgkin’s-like nodal lymphoma usually
tional state, caloric intake, and body weight should be under- present without overt clinical signs. 541,542 Inguinal node, multi-
taken. Nutritional support (see Chapter 16, Section B) should be centric nodal, subcutaneous, and conjunctival involvement have
instituted sooner rather than later in affected cats. A good plan of been reported. 542–545 Interestingly, in both reports of subcutane-
nutrition should help maintain or improve quality of life, immu- ous Hodgkin’s lymphoma in cats, spontaneous remissions were
nologic status, and tolerance of chemotherapy. Cobalamin sup- observed suggesting these may not have been be true lymphoid
plementation should be instituted in those cats with documented neoplasia. 543,544 The clinical course of Hodgkin’s like lymphoma is
hypocobalaminemia. generally more indolent than for peripheral nodal non-Hodgkin’s
lymphoma in the cat.
Peripheral Nodal Lymphoma in Cats The treatment choice for peripheral nodal lymphoma in
cats depends on whether the individual case represents a low-
Involvement limited to peripheral lymph nodes is unusual in cats with grade (e.g., indolent [rare]) versus an intermediate- or high-
lymphoma, representing approximately 4% to 10% of cases. 427,428 grade (e.g., intermediate/large cell) lymphoma; the latter are