Page 164 - Canine Lameness

136 11 Diagnostic Approach to Neoplastic Conditions Causing Lameness

Consider for staging
(based on biologic
behavior of tumor) Neoplasia
causing Consider to establish
lameness diagnosis
CBC/chem
Physical exam

Thoracic
radiographs
FNA
Removal of
tumor
Abdominal
radiographs Radiographs of
tumor

Lymph node
aspirate Final diagnosis
Advanced imaging

Abdominal
ultrasound
Biopsy
Determine need
for further
Advanced imaging treatment

Figure 11.1 Schematic representation of the clinical approach to a patient exhibiting lameness caused by
neoplasia. The veterinarian should attempt to establish a diagnosis for the primary tumor and determine
the extent of distant disease (staging). The biologic behavior of the tumor influences the appropriate
diagnostic methods (for example, advanced imaging may not be necessary for all tumor types).

with cytology, this does not rule out the possibility of neoplasm and another attempt at FNA or a
biopsy is necessary. In one study, Ghisleni et al. (2006) reported that the cytology of cutaneous and
subcutaneous masses agreed with the histologic diagnosis in 90% of the diagnostic samples
obtained. Similarly, in a retrospective study that compared the accuracy of using cytology and
histological biopsies to diagnose destructive bone lesions, Sabattini et al. (2017) observed non‐
accurate results in about 20% of the cases for each technique, thus suggesting that cytology is a
valid alternative to histology. When results suggest a false negative (e.g. reactive bone; which has
been reported to occur in up to 17% of biopsies of malignant bone tumors), it is recommended to
repeat the biopsy (Powers et al. 1988; Sabattini et al. 2017). Yet, even this may be nondiagnostic in
some cases, and a final diagnosis can only be obtained once the entire lesion is removed (e.g. via
amputation or limb sparing). Ultrasound guidance can be helpful to increase the likelihood of
acquiring a diagnostic sample with an FNA for bone lesions (Britt et al. 2007). With ultrasound,
breaks in the cortex can be found and used to guide the needle into the intramedullary component
of the tumor. Tumors that have a significant soft tissue component may be successfully aspirated
without ultrasound guidance. If cytology of a bone lesion is obtained, alkaline phosphatase (ALP)
staining can be performed. ALP staining is highly sensitive but not entirely specific for osteosarcoma