Page 50 - VetCPD Jnl Volume 7, Issue 4

VETcpd - Surgery
but this may be related to the tumour grade, with recurrence rates being much higher for intermediate- and high-grade than for low-grade tumours (Ettinger et al. 2006; McSporran 2009). Until further studies are performed to evaluate these results, marginal excision cannot be recommended over wide surgical excision if it can be achieved anatomically.
Until or unless a means is found to predict the size of margin resection for individual soft tissue saromas, wide excision with 2-3-cm skin and lateral margins and a clean deep fascial margin is performed, where possible anatomically. A clean deep fascial plane is defined as fascia that hasn’t been invaded by the mass.Wide margins can usually be obtained on the trunk
and proximal limbs. It is recognized that
this approach may mean that some dogs
have wider resections than are necessary
to obtain clean margins. However, this is
A
Figure 3: CT scan of the thigh of the dog in Figure 1. A large mass is present on the cranial thigh and
is contiguous with or has invaded the rectus femoris muscle (RF), which must be removed to achieve a deep margin.
Figures 4A-C: Soft tissue sarcoma on the craniolateral thigh of a dog. Wide lateral margins have been taken as well as a fascial layer deep to the mass, which includes part of the fascia of the biceps femoris muscle. The wound has been closed primarily without need for advanced reconstructive procedures.
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considered preferable to taking a smaller
margin that fails to resect all tumour cells,
Some owners may choose not to have surgery performed on their dog, be unable to afford surgery, or the patient
as further surgery or adjunctive therapy
will be needed. In some cases, further
surgery or adjunctive therapy may not be may be elderly or have co-morbidities
possible due to availability of local tissues that preclude surgery. Most soft tissue
for resection and closure, lack of access to sarcomas don’t cause pain to the
adjuvant therapies, or costs the client can’t animal, so euthanasia is generally not meet, in which case the original surgery Onlynecessary for a dog where surgery is not
B
The exception to the large margin
approach is the distal extremities, where
there is usually no deep fascial plane
available for resection, or where taking
the deep margin may compromise limb
function. In these instances, there may be
little to gain from wide lateral margins, as
the deep margin is often dirty (positive for tumour cells on histopathology) and the
defect can often not be closed primarily.
Instead, a marginal lateral excision is
performed. Studies report that marginal
excision may be comparable to wide
surgical excision, with low recurrence
rates, especially for low-grade tumours C (grades 1 and 2) and tumours distal to the
elbow (Stefanello et al. 2008, Demetriou
et al. 2012).The latter may reflect the
tendency for soft tissue tumours of the extremities to be small at the time of
diagnosis, and low-grade, both of which
are positive prognostic factors. It is
generally not necessary to consider limb amputation for limb soft tissue sarcomas,
and amputation is unlikely to increase
survival times; exceptions may include
invasive tumours, ulcerated or ruptured
tumours or painful inoperable tumours.
Page 46 - VETcpd - Vol 7 - Issue 4
possible. Many elderly dogs will die of a comorbidity, without the tumour having caused them suffering.
Advanced imaging can be useful to plan surgery, in particular to determine if a deep margin can be achieved, and to plan what tissue to remove (Figure 3).
Depending upon the size and location of the mass, wound closure may be achieved primarily after undermining (Figures 4a-c), or advanced reconstruction procedures may be necessary (Figures 5a-d).
Following marginal excision of sarcomas of the extremities, defects can often be closed primarily (Figure 6). If the defect is too large for primary closure, it can be left to heal by second intention healing, which is often complete within a few weeks (Figures 7 and 8).
As incisional biopsies can over- or underestimate grade compared to excisional biopsy, the excised tumour should always be submitted for further histopathology.The mass is submitted in its entirety, as many areas of tumour can be necrotic, and extent of malignancy may differ throughout the mass; large specimen pots will be needed. Partial thickness incisions are made into large masses from the deep surface to allow
will have failed and the dog will have suffered unnecessary morbidity.