Diagnostic
Imaging Quiz
Question:
A 5-year-old horse is presented
with a granulating wound on the
palmarolateral aspect of the proximal LF
metacarpus, with a draining sinus tract.
Evaluate the accompanying radiograph.
a)
b)
c)
d)
Name the radiographic view.
Which additional ONE radiographic
view should next be taken to add
more information?
List the radiological changes present.
What is the diagnosis?
Answer on page 27
biopsy should include both the neoplastic tissue and
its interface with normal appearing skin (Fig 4). Local
lymph nodes should be assessed clinically (including
iliac lymph nodes, which can be palpated per
rectum) and if lymph node involvement is suspected,
fine needle aspirates and/or biopsies should be
performed when possible to assess metastasis.
Secondary spread to regional lymph nodes may
support a poor prognosis and may influence the
decision to initiate treatment.
In man, several variations of SCC grading have been
described (Chaux et al. 2009; Sobin et al. 2010).
Equine MC-SCC have been evaluated and grouped
by differentiation grade, following histopathological
characteristics used in human medicine (Chaux et
al. 2009). This criteria defines G1 (grade 1) lesions
as well-differentiated tumours, with neoplastic cells
nearly identical to normal or hyperplastic squamous
cells. In contrast, G3 (grade 3) lesions are considered
poorly differentiated with anaplastic squamous
cells that contain high nuclear : cytoplasmic ratio,
numerous mitotic figures, clumped chromatin and
prominent nucleoli. Grade 2 (G2) tumours describe
moderately differentiated squamous cells and
do not fit into criteria described for either G1 or
G3 lesions. In a recent study, 81 equine MC-SCC
were grouped by differentiation grade based on
histopathology; metastasis was confirmed in 44% of
tumours graded as G3, compared to 25% forG2and
only 3% for G1. Eighty percent of the G3 tumours had
an unsuccessful outcome (i.e. tumour recurrence or
euthanasia; van den Top et al. 2011). Taken together,
these data suggest that the G1–G3 grading scale may
be beneficial in characterising equine MC-SCC and
predicting outcome in affected horses.
Treatment
Several modalities have been recommended
for treatment of equine MC-SCC; these are most
successful when treatment is initiated early in the
course of disease. Surgical management, cryotherapy,
hyperthermia, radiotherapy, chemotherapy and
photodynamic therapy are used with degrees of
success relative to the accessibility and invasiveness
of the tumour.
Conventional excision
Ann Carstens, BVSc, MS, MMedVet(Large Animal
Surgery), MMedVet (Diagnostic Imaging), DTE, PhD
26
Surgical excision is typically performed on tumours
in which a satisfactory surgical margin of 0.5–1.0 cm
can be achieved; however, higher rates of recurrence
have been reported with excision of ocular MC-SCC
without concomitant use of adjunctive therapy
(King et al. 1991; Mosunic et al. 2004). Therefore,
adjunctive treatments are often used following
surgical debulking of MC-SCC. Depending on size
and location of male genital MC-SCC, surgical
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