Page 184 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 9 Biopsy and Sentinel Lymph Node Mapping Principles 163

13. A veterinary-trained pathologist is preferred over a patholo- 2. If the tumor is still present in the patient, and particularly
gist trained in human diseases. Although many cancers are if widely varied options exist for therapy, a second (or third)
biopsy should be performed.
histologically similar across species lines, enough differences
VetBooks.ir In 2011 the American College of Veterinary Pathologists, most important step in management and subsequent prognosis
exist to result in interpretive errors.
A carefully performed, submitted, and interpreted biopsy is the
along with several medical and surgical oncologists, published a of the patient with cancer. The biopsy report is key in decision
comprehensive set of recommendations and guidelines for sub- making regarding therapeutic options, prognosis, and overall case
mission, trimming, margin evaluation, and reporting of tumor management. All too often tumors are not submitted for histo-
biopsy specimens. This landmark paper was the first collaborative logic evaluation after removal because “the owner didn’t want to
6
attempt to standardize pathology reporting in veterinary oncol- pay for it.” Histopathology interpretation should not be an elec-
ogy and has been endorsed by a large international group of vet- tive decision. Instead, it should be as automatic as closing the skin
erinary pathologists and oncology specialists. It is recommended after surgery. The charge for submission and interpretation of the
that clinicians utilize diagnostic laboratories that adhere to these biopsy should be included in the surgery fee, but histopathology
guidelines so that results are standardized and easier to interpret. interpretation is not optional. Because of increasing medicolegal
concerns, it is not medical curiosity alone that mandates knowl-
Interpretation of Results edge of tumor type. Understanding how and when to perform
a biopsy, how to submit a biopsy specimen for histopathologic
The job of the pathologist is to determine (1) tumor versus no interpretation, and how to interpret the report are of paramount
tumor, (2) benign versus malignant, (3) histologic type, (4) his- importance in the treatment of veterinary cancer patients.
tologic grade (if available clinically), and to (5) assess surgical
margins (if excisional biopsy). Making an accurate diagnosis is References
not as simple as putting a piece of tissue in formalin and wait-
ing for results. Many pitfalls can occur to render the end result 1. Ghisleni G, Roccabianca P, Ceruti R, et al.: Correlation between
inaccurate. Potential errors can take place at any level of diagnosis fine-needle aspiration cytology and histopathology in the evaluation
and it is up to the clinician in charge of the case to interpret the of cutaneous and subcutaneous masses from dogs and cats, Vet Clin
full meaning of the biopsy result. In cases in which the biopsy Pathol 35:24–30, 2006.
result does not correlate with the clinical behavior of the tumor, a 2. Sharkey LC, Wellman ML: Diagnostic cytology in veterinary medi-
second opinion should be requested. A study published in 2009 cine: a comparative and evidence-based approach, Clinics Lab Med
reviewed first- and second-opinion histopathology reports. There 31:1–19, 2011.
7
was diagnostic agreement between first and second opinions in 3. Worley DR: Incorporation of sentinel lymph node mapping in dogs
70% of cases. In 20% of cases, there was partial agreement, where with mast cell tumours: 20 consecutive procedures, Vet Comp Oncol
12:215–226, 2014.
the diagnosis did not change but information such as grade or 4. Brissot HN, Edery EG: Use of indirect lymphography to identify
presence of lymphatic or vascular invasion was disparate. In 10% sentinel lymph node in dogs: a pilot study in 30 tumours, Vet Comp
of cases, there was complete diagnostic disagreement. Of these, Oncol 15:740–753, 2017.
7% were a disagreement between malignant versus nonmalignant 5. Whitehair JG, Griffey SM, Olander HJ, et al.: The accuracy of
disease and 3% were disagreements about the cell of origin of the intraoperative diagnoses based on examination of frozen sections. A
tumor. If the biopsy result does not correlate with the biologic prospective comparison with paraffin-embedded sections, Vet Surg
behavior of the tumor, several options are possible: 22:255–259, 1993.
1. Call the pathologist and express your concern over the biopsy 6. Kamstock DA, Ehrhart EJ, Getzy DM, et al.: Recommended guide-
result. This exchange of information should be helpful for both lines for submission, trimming, margin evaluation, and reporting of
parties and not looked upon as an affront to the pathologist’s tumor biopsy specimens in veterinary surgical pathology, Vet Pathol
48:19–31, 2011.
authority or expertise. It may lead to 7. Regan RC, Rassnick KM, Balkman CE, Bailey DB, McDonough SP:
a. Resectioning of available tissue or paraffin blocks Comparison of first-opinion and second-opinion histopathology from
b. Special stains for certain possible tumor types (e.g., tolu- dogs and cats with cancer: 430 cases (2001-2008), Vet Comp Oncol
idine blue for mast cells) 8:1–10, 2010.
c. A second opinion by another pathologist