Page 181 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

160 PART II Diagnostic Procedures for the Cancer Patient

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• Fig. 9.2 Mechanism of action of punch biopsy. (A) The instrument is applied with pressure and back and
forth rotation to allow the instrument to penetrate the mass. (B) The punch is removed or angled across
the base to sever the deep attachment. (C) If needed, the specimen can be gently grasped with forceps
and cut at the base with metzenbaum scissors.

the punch has cut into the tumor, the core is gently lifted, and the accuracy in diagnosis on histopathologic examination. Although
base of the core is cut off with scissors. One or two sutures may be this may be helpful to the pathologist in benign skin disease and
placed to close the incision and tamponade bleeding. subtle lesions, it is not recommended in cases in which neopla-
sia is suspected, as this may result in extending the biopsy inci-
Incisional Biopsy sion into previously uninvolved tissues. This can compromise
the surgical margins needed to remove the mass entirely at the
Incisional biopsy is utilized when neither cytology nor needle-core time of definitive surgery and exposes previously uninvolved tis-
biopsy has yielded diagnostic material (Fig. 9.3). Incisional biopsy sues to freshly incised tumor. Instead, a representative sample of
is also preferred for ulcerated and necrotic lesions because larger the tumor itself should be submitted. This may require obtaining
samples can be obtained, making it more likely for the surgeon to multiple samples via the same incision to ensure that a representa-
sample representative areas. Most tumors are very poorly inner- tive sample has been achieved. Care must be taken to ensure that
vated and may be biopsied without the need for local anesthesia any biopsy tract (incisional or other) will not compromise sub-
or sedation as long as the overlying normal skin and tissue has sequent curative-intent resection, contaminate uninvolved tissue
been anesthetized. Preparation involves clipping the hair over the needed for reconstruction, or compromise subsequent radiation
incision site. After an aseptic preparation is made, surgical drapes therapy. The surgeon should avoid widely opening uninvolved tis-
are used to protect the field from the surrounding environment. sue planes that could become contaminated with released tumor
Under aseptic conditions, the skin, if intact over the tumor, is cells. Small incisions, even through expendable muscle bellies, are
incised and a wedge of tumor tissue is removed from the mass. preferred to contaminating an entire intramuscular compartment.
It is not necessary to remove a wedge of intact skin overlying the The incisional biopsy tract is always removed in continuity with
tumor if it appears to be normal and not fixed to the underlying the tumor at the time of curative-intent resection.
tumor. It is important for the surgeon to confirm at the time of
the biopsy that he or she has not simply removed a small section Specialized Biopsy Techniques
of the reactive tissue surrounding the tumor. This can be difficult
in some cases; however, most tumors have coloration and texture Specialized biopsy techniques will generally be covered under spe-
that is distinct from that of the surrounding normal and reactive cific individual tumors. However, some general comments follow.
tissue. If needed, cytologic assessment of touch impressions can be
made using the resected tissue to confirm that neoplastic cells are Endoscopic Biopsies
present in the removed tissue. These techniques use flexible or occasionally rigid scopes that
Many authors have recommended that the surgeon acquire allow visualized or blind biopsy of hollow lumens, especially gas-
a composite biopsy of normal and abnormal tissue to assure trointestinal, respiratory, and urogenital systems. Although these