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BE PATIENT
Most diagnostic histopathology laboratories offer a
24 hour turn-around for routine biopsy submissions,
but the clinician should appreciate that non-standard samples require more complex processing and it will therefore take longer to generate a result. A large (e.g. orange-sized) or very soft tissue sample may require additional fixation in the laboratory before processing or a ‘long process’ over several days rather than overnight. Tissues including areas of bony metaplasia or samples including bone (e.g. digit removal, bone tumours) will require prolonged decalcification before the tissue is soft enough to process and section. Decalcification of bone may take many weeks.
UNDERSTAND THE LANGUAGE OF THE PATHOLOGIST
Once the pathology report is sent to you, do take the time to read and understand the complete report. Many clinicians will read only the ‘bottom line’ (i.e. the diagnosis) or the ‘comments’ section of a report and skip the actual descriptive report. Much information is conveyed in that description, particularly assessment of marginal infiltration or metastatic activity. Pathologists do use a very specific language to convey degrees of certainty (and this has been studied and published) and you should understand the way that your pathologist uses terms such as ‘consistent with’, ‘not inconsistent with’, ‘probable’, ‘likely’ and others.
COMMUNICATE WITH YOUR PATHOLOGIST
This is the most important of all. If anything is unclear
or the pathological report does not match your clinical expectations then do not be afraid to telephone
your pathologist to discuss the case. This exercise
is of mutual benefit. The pathologist should be able
to advise on whether further sectioning of the gross specimen is justified, or whether special histochemical, immunohistochemical or molecular studies might be performed. For some infectious agents it is now possible to take samples from the wax-embedded tissue for PCR diagnosis and molecular tests for cancer characterization are now routinely available. Many pathology laboratories can now readily provide digital images of the histopathology to help your understanding. Finally, no pathologist will be offended if you ask for a second opinion on a slide and should be able to advise on an appropriate colleague to provide that opinion.
Further Reading
Cade S. Sending diagnostic samples: your questions answered. In Practice. 2010. 32: 312-314.
Stidworthy M, Priestnall S. Getting the best results from veterinary histopathology. In Practice. 2011. 33: 252-260.
Your Singapore, the Tropical Garden City
WSV18-0173
ISFM - FELINE CARDIOLOGY
CARDIAC NEOPLASIA IN CATS: EXPECT THE UNEXPECTED
K. Borgeat1
1Langford Vets- University of Bristol, Cardiology, Bristol, United Kingdom
Measurement of N-terminal pro-B type natriuretic peptide (NTproBNP) and cardiac troponin I (cTnI) has now become commonplace in general and referral practices. These assays offer a straightforward and accessible test, which often feature in the diagnostic investigation of feline cardiac disease by veterinarians in general and referral practice alike. However, our understanding of the clinical utility of these laboratory tests is ever evolving as more research in the area is published.
Table 1 highlights common clinical scenarios in which cardiac biomarkers may be measured, and briefly summarises the evidence behind the noted utility (table 1 is at the end of this section).
Clinical use of the patient-side NTproBNP SNAP test: can it help to identify which heart murmurs to investigate?
A potentially useful test for assessing which heart murmurs to investigate and which to monitor/reassess in time is the patient-side NTproBNP SNAP test. It may also be useful as part of pre-anaesthetic screening in geriatric cats, where heart disease is common.
This test was validated by comparing a population of cats with moderate to severe cardiomyopathy (“clinically significant”) to a population of cats with either normal echos or mild cardiomyopathy (“not clinically significant”) (Machen et al, 2014). The SNAP test works well on EDTA plasma and has a positive cut-off value of approximately 120 pmol/L NTproBNP. If the value is negative, the NTproBNP is probably < 100 pmol/L. Occasionally it may read equivocal if between these values.
The test performed well in validation. To get a feel for how clinically useful the test is in asymptomatic cats with heart murmurs, we should consider the test specifics
by Machen et al and combine these data with the prevalence data from Payne et al (Table 2).
In summary, a negative test is highly likely to mean that
a cat does not have significant heart disease. A positive test is less useful, but it means that echocardiography is indicated (or even just monitoring of respiratory rate, care with intravenous fluids, cautious selection of sedation/ anaesthesia protocols, etc – if echo is prohibited by cost or local access to expertise). In older cats, a positive
test is associated with a greater likelihood of clinically significant heart disease being present.
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