Page 1343 - Small Animal Internal Medicine, 6th Edition

CHAPTER 80 Leukemias 1315

WBC Run WBC Run
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Fluorescence Fluorescence

Granularity Granularity
A NEU LYM MONO EOS BASO URBC B NEU LYM MONO EOS BASO URBC

C D

FIG 80.4
White blood cell dot plot from a ProCyte Dx in a dog with acute leukemia (A) compared
with a normal dot plot (B). Note the funnel-shaped monocyte curve in red, in contrast with
the well-defined, upward tapering cloud in B. The numeric values in this dog consisted of
moderate neutropenia (0.96 × 10 /L), mild monocytosis (2.5 × 10 /L), and moderate
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thrombocytopenia (49 × 10 /L). Monocytoid blast in peripheral blood (C). Bone marrow
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cytology reveals monocytoid precursors with a tendency toward myeloid/myelomonocytic
differentiation (D). The final diagnosis was acute myeloid leukemia.

and clinicopathologic information (i.e., the degree and extent may be difficult to distinguish on the basis of the clinical,
of lymphadenopathy, presence and degree of hepatospleno- hematologic, and cytologic information obtained, but the
megaly, hematologic and bone marrow biopsy, or aspiration guidelines found in Box 80.1 can be used to try to arrive at
findings) is required to establish a definitive diagnosis. a definitive diagnosis. Immunophenotyping can also be used
It may be difficult to diagnose the specific tumor type to distinguish these two entities.
in a dog with generalized lymphadenopathy, hepatospleno- When the neoplastic cells are poorly differentiated, cyto-
megaly, and a low number of circulating lymphoblasts. The chemical staining or immunophenotyping is required to
main differential diagnoses are ALL and lymphoma with establish a definitive diagnosis (see Table 80.2). This is
circulating blasts (leukemic phase of lymphoma). It is impor- important if the owner is contemplating treatment because
tant to differentiate between these two disorders because the the therapy and prognosis for dogs with AML are different
prognosis for dogs with lymphoma is considerably better from those for dogs with ALL (i.e., the survival time in dogs
than that for dogs with acute leukemia. These two entities with AML is shorter than that in dogs with ALL).