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Diagnosis and Staging


Neoplasic tissues have certain characteristics that make them differ from hyperplasias or inflammatory alterations. Another aspects allow the professional to differentiate between benign or malignant neoplasias



Although and experimented veterinarian may guess the type of tumor based on its localization, macroscopic aspects and records, final diagnosis can only be achieved under an microscopic evaluation of a representative sample. Following techniques can be used:


-  Tumor tissue biopsy - Histopathologic diagnosis.

-  Tumor cell biopsy - cytological diagnosis.



Treatment and prognosis for every patient will depend on nature and extension of the illness. Hence, for a successful therapy, histopathology, grade, size and anatomical extension of the tumor should be described previously.

It is also important to try to identify possible hematological or metabolic complications related with the disease, and investigate the presence of a concomitant disease, as all these variables may have influence in treatment choice and prognosis, or even define whether the patient has a therapeutic possibility or not


The objectives of initial evaluation of the patient are summarized as follows:

Histopatologic type diagnosis and disease grade

Determine extension and disease stage

Investigate possible complications related with tumors

Investigate any concomitant disease or alteration


Cancer diagnosis ¿What is Histopathology?  

The most efficient method for tumor diagnosis is microscopic analysis (biopsy). In order to do this, it is necessary to obtain a small sample, process and examine it by an expert, who should be able to identify exclusive characteristics of each tumor variant. These are associated with the origin and growth of each one. Neoplasias always have differences, and as sometimes they are subtle, it is possible that the professional may get confused.

Another important aspect is to do a precise diagnosis of benign and malignant tumor variants.

With the exception of leukimias, that affects leucocytes and therefore the diagnosis is made after analyzing slides of blood and bone marrow, all other neoplasias are analyzed from a sample of the solid tumor. These are the routine procedures, which have improved within the last 150 years, and have became very popular, since they are the most quick, cheap and effective way to diagnose the variants. The denomination of this procedure is Histopathologic examination, and it is based on the fact that every neoplasic proliferation has a microscopic "face". This shows a special histopathology that corresponds to a specific "type" of disease. The knowledge of this allows the exact diagnosis, hence being able to study its biology and designing a specific treatment for it.

During the microscopic analysis, the light that passes through the sample gives the possibility to see the different shapes, colors, and structures. Molecular structure is not seen under this equipment. This method is called neoplasia histology.

If a digital picture is taken, it could now be analyze by experts all around the world within minutes (using Internet)

After the sample is taken, the next step is to analyze it using the microscope. This is performed by veterinary pathologists. Since the final report is crucial for diagnosis, the professional should be an expert, and this takes years to achieve. For each case, patient's characteristics must be taken into account (age, gender, lesion localization, lab results, imaging results, race, etc.). Statistics of tumors in different regions or tissues is also something to consider. All these become crucial when differences are extremely subtle.

To make the scenario a little worse, periodic publications announce the discovery of subvariants of histological patterns, that define special entities. This should not be mistaken for benign or malignant categories. Therefore, constant updating and congresses attendance are almost mandatory.

Diagnostic errors could bring serious problems for everyone. These situations have led pathologists to become aware of the following saying: "Histological preparation is never wrong", which underlines that the mistake always comes from subjective evaluation of the observer.

Veterinary pathologists are responsible for appropriate working methods in laboratories. The results given by these should be the most exact, precise and objective as possible. The clinical veterinarian will receive and analyze the report handed by the pathologist. Writing must be clear in order to be able for almost any good veterinarian to understand it. As easy as it sounds, this is not common in practice. Once the diagnosis is clear, the professional can offer to owners the treatment choices.

Histopatologic method simplicity, speed and reproducibility have led to its universal adoption. Its success, nevertheless, has not depended on these advantages exclusively. The capacity to answer to growing demand using a cheap method with exactitude was key for its popularity.