Page 37 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery

that can be incorporated in a definitive resection. The • Core sampling instruments: These are used for
accuracy of diagnosis increases with increasing volume of superficial masses or for those masses that can be
VetBooks.ir tissue contamination. If the biopsy results do not correlate • Disposable punch biopsy instruments: Because
tissue submitted, but so does the risk of biopsy-induced
palpated well enough to be stabilized during biopsy,
and also for lymph nodes.
with the clinical findings, a deeper and larger biopsy speci-
men should be obtained.
The systematic examination of a primary tumour, lesions may be hidden beneath a layer of normal tissue,
open-ended skin biopsy punches are useful for
regional lymph nodes and any distant metastasis – the so- obtaining deep samples (Figure 3.1).
called TNM (tumour, node, metastasis) system – provides • Incisional biopsy: This is performed using a scalpel
a method of describing the clinical extent (staging) of a blade to obtain a wedge of tissue. Incisional biopsy
malignancy and is an essential prerequisite for rational should not be performed in areas of ulceration,
treatment of oral tumours (Arzi and Verstraete, 2012). necrosis or inflammation, as the tissue obtained may
Obtaining and examining a biopsy specimen allows the not be representative of the actual lesion.
clinician to establish the diagnosis, formulate a treatment • Excisional biopsy: The biopsy procedure may be
regimen and give the owner an accurate prognosis. curative as well as diagnostic. Keeping in mind that the
first attempt at surgical resection of a malignancy has
Sampling for cytology: Cytological samples can be the best chance for cure, excisional biopsy may be
obtained from awake or sedated patients. The two most indicated for smaller masses and lymph nodes that can
obvious examples of oral lesions that can be diagnosed easily be excised en bloc.
cytologically are SCC and eosinophilic granuloma.

• Fine-needle sampling (‘woodpecker method’) and
fine-needle aspiration: Fine-needle techniques have
some value for oral lesions. Cytological examination of
lymph node aspirates may be adequate for diagnosing
metastatic melanoma and SCC but is less satisfactory
for other oral tumours (Herring et al., 2002).
• Impression smears: Smears obtained from the
surface of an ulcerated tumour often have low
diagnostic value, as imprints may harvest only bacteria
and superficial inflammatory cells and not the
underlying tumour cells. Impression smears may be of
greater value if taken from the cut surface of a tumour.
• Scrapings: Cytological examination of oral tissues can
be useful if the sample is scraped from cut tissue
surfaces. This technique may also be suitable for firm
ulcerated lesions that are unlikely to exfoliate well using
fine-needle techniques.
Sampling for histology: Surgical biopsy under general unch biopsy of a fibrosarcoma at the rostral ma illa in a dog.
anaesthesia and microscopic examination of a formalin- 3.1 T o previous biopsies had indicated a peripheral odontogenic
fixed specimen provide a more accurate diagnosis than fibroma. small mucoperiosteal flap as created to obtain a deeper
cytological sampling techniques. Electrosurgical/radio- tissue sample.
surgical equipment, laser and other tissue-damaging tech-
niques should be avoided so as not to obscure a diagnosis.
Areas of superficial necrosis should be avoided so that the Benign neoplasms
sample contains deeper, viable tissue. It is rarely satis- Canine viral papillomatosis
factory to snip a small piece from the most protuberant
area, even though it is tempting to do so in the consulting Papillomas appear on the oral mucosa as pale, smooth
room as a means of avoiding anaesthesia and expediting elevations that develop a rough surface early in the disease
the diagnostic process. Multiple samples are preferred, as process. Older lesions of 3–4 weeks’ duration usually have
a single sample may not be representative. Haemostasis is deep and closely packed fronds. Lesions observed during
achieved by digital pressure. Continuously bleeding biopsy regression appear shrivelled and dark grey. Complete
sites and sampling locations in more deeply invading and regression may take several weeks but typically leaves no
pharyngeal tumours should be sutured with a pattern scar. Papillomas that interfere with prehension, mastication
(cruciate or mattress) that promotes compression. and swallowing should be removed. Azithromycin seemed
For adequate fixation, the biopsy sample is placed in to have an accelerating effect on the regression of papillo-
10% buffered formalin at 1 part tissue to 10 parts fixative mas in dogs in one study ( a ci et al., 2008).
(White, 2003a). For diagnosis of suspected autoimmune dis-
orders by direct immunofluorescence, a specimen should Odontogenic tumours
be obtained from the most active area of disease, ideally
with an intact epithelial vesicle, and should include adjacent These tumours are often located in the gingiva near the inci-
grossly normal epithelium. The sample is placed in Michel’s sor, canine or premolar teeth, or the mandibular first molar.
preservative instead of formalin (Harvey and Emily, 1993).
• Peripheral odontogenic fibromas (previously called
• Grab sampling instruments: Straight alligator or fibromatous and ossifying epulides) are pedunculated,
oval/round cup forceps are used for less accessible non-ulcerating and non-invasive masses (Figure 3.2),
pharyngeal tumours. Rongeurs are very useful for containing varying amounts of bone, osteoid, dentinoid
obtaining samples from firm or bony tissue. or cementum-like tissue.

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