The Daily Life of a Pathologist

By Marcia R S Ilha, DVM, MSc, DACVP

Veterinary pathologists are challenged daily with making a diagnosis on a variety of surgical biopsies. Many times clinicians will opt for surgical biopsy hoping for a definitive diagnosis that will give relevant information for therapy and prognosis. The pathologist becomes that one person from whom clinicians and owners wait for an answer. At times, however, the histological findings are inconclusive. Some examples of challenging diagnoses are discussed below.

Inflammatory bowel disease: There is still extensive debate on how many and which inflammatory cells would be considered “normal” in the lamina propria of intestinal biopsies. Inflammatory bowel disease is a very challenging diagnosis and a general diagnosis of “enteritis” can be easily made in many biopsies depending on the evaluation criteria used by the pathologist. Recently the World Small Animal Veterinary Association Gastrointestinal Standardization Group published standard templates for the histopathologic diagnosis of gastrointestinal inflammation in endoscopic biopsies from dogs and cats. The standardization is an attempt to facilitate the reporting of microscopic changes in biopsy samples and to reduce variation between the interpretations of different pathologists. However, this is still a controversial area.

Splenic hemangiosarcoma: One of the most frustrating diagnoses for pathologists, clinicians, and owners is the “elusive” splenic hemangiosarcoma. Many times the biopsy report will come back as “no neoplasia found” or the final diagnosis is simply of “splenic hematoma.” Clinicians however are still suspecting splenic hemangiosarcoma and will ask for additional sectioning. After several histological sections being examined and several recuts being made the diagnosis is still of a hematoma. Hemangiosarcomas have a tendency to give origin to large hematomas and areas of necrosis, and many times the neoplasm cannot be identified in the tissues. A diagnosis of splenic hematoma without a specific underlying cause such as nodular splenic hyperplasia or trauma may be still an indication of the presence of hemangiosarcoma in animals in which presentation and hematological findings are suggestive.

Bone core biopsy: Often the clinician is concerned with a neoplasm or inflammatory process in an osteolytic lesion and receives a report of normal or reactive bone. It is very frustrating for pathologists to report that “no lesions are found” from a specimen. Very often the samples are collected from areas of reactive bone at the periphery of the lesion and therefore a diagnosis is impossible.

Chronic skin disease: Clinicians have to be aware that very often the pathologist will report back what they already know, a diagnosis of “chronic skin disease” with a long list of possible differential diagnoses or none at all. In many cases a skin biopsy is performed after the animal has undergone topical or systemic treatment with multiple combinations of antibiotics, steroids, and anti-inflammatory drugs. As with other organs, there are many general reactions of the skin to injury that are not indicative of any particular disease and can be seen in chronic skin diseases of multiple etiologies. The acute skin lesion usually provides the most information and best chance for an accurate diagnosis.

Artifact: Another common problem in surgical biopsies is artifact. Eletrocautery or laser heat artifact is a crucial problem with small biopsies. It can destroy a large portion of the tissue and can result in non-diagnostic samples, misdiagnoses, or interfere with the surgical margin evaluation.

Practitioners should consider the above mentioned factors when submitting a biopsy. Always remember that the results from a surgical biopsy should be combined with the clinical presentation to reach an accurate diagnosis, prognosis, and select treatment options.

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