Mac-ximizing Diagnostics: Blood Cell Conundrum and Effusion Confusion

Overview

A surprise finding on the blood film leads the health care team down an interesting path.

Case Details and History

Mac, a sighthound, came to the animal hospital on referral for “an irregular spleen, possible lymphoma,” presenting with an acute abdomen. He had a history of being anorexic and lethargic. In obvious abdominal discomfort, Mac stood in “prayer position” with his elbows down and hips in the air to stretch out his painful abdomen.

Physical Exam

Other than Mac’s discomfort in response to abdominal palpation, there were no other significant abnormalities.

Diagnostic Process

• Mac’s CBC did not show a traditional inflammatory leukogram with a leukocytosis (increased total white cell count) and a neutrophilia (increased total neutrophil count). However, the Element HT5+™ did report he did have bands identified, which is the hallmark of inflammatory disease.
• Leukogram: In Mac’s case, no significant numerical abnormalities were in the erythrogram. Platelet parameters were also within the reference interval.
  • The leukogram revealed a monocytosis in support of tissue destruction, and a superimposed stress response that decreased lymphocytes and eosinophils.
  • Additionally, the WBC scattergram from the Element HT5+™ revealed both a left shift, as well as an abnormal cell population, prompting a blood film review for further insights.

Pro Tip: Automated hematology analyzers are trained on normal samples and will be challenged in recognizing and accurately identifying abnormal cell populations, either because the cell type is unexpected, or they have significant morphology changes.

• At the reference lab, abnormal cell populations creates flagging that results in a technologist’s or pathologist’s review of a blood film for amended results.
• At point of care, it is essential to use the cytograms that accompany the numerical data to provide insights into cell abnormalities. Learning species-matched “normal” scattergrams and histograms for your particular analyzer is important to recognize abnormal changes. It is recommended to run a healthy dog and healthy cat sample to capture an example of normal that can be used as a comparison to sick patient samples. When the cytogram patterns do not match the normal samples, that should prompt a blood film review for further insights. The Element HT5+™ generates abnormal cell morphology flags that are displayed on the analyzer to alert you to significant changes. With practice, you will be able to learn what the more common pattern changes reflect and can use that information to make more accurate interpretation and diagnoses.

• With very sick patients, pairing a blood film with the CBC is best practice. As it turned out, the blood film in Mac’s case revealed massive clues to his condition.
  • Finding: Observed on Mac’s blood film review were bands with toxic change, supporting a systemic inflammatory process, and activated-appearing monocytes in support of tissue destruction. Additionally, infrequent large cells with big round nuclei and prominent purple granules were observed, consistent with mast cells in circulation.

• In Mac’s case, the concern was systemic inflammatory process, possible GI compromise, especially given his abdominal pain. And there were mast cells in circulation — which, most commonly, are part of a nonspecific inflammatory response. But Mac’s abnormal WBC scattergram showed this abnormal mast cell population to be a prominent change, and the team was concerned that Mac might have underlying mast cell neoplasia.
• The ultrasound showed an irregular spleen that was bumpy and mottled looking, very nodular throughout the surface, with a scalloped margin. Additionally, a significant amount of ascites was noted.

Pro Tip: When an animal presents extremely sick, however, they’re commonly dehydrated — likely not eating or drinking, and possibly vomiting — and a flash ultrasound or detailed ultrasound may not show any effusion. But once the animal is rehydrated, an ultrasound should be repeated to identify potential ascites.

With critical patients like Mac who have acute abdominal pain and ascites, decisions need to be made quickly, but not hastily, to obtain a diagnosis and appropriate treatment plan. For Mac, surgery was a possible next option, but determining what was going on inside the abdomen would help give his owner more information before making the decision to take him to surgery.

Effusion analysis can provide a wealth of information on what’s happening in a sick patient.

• For Mac, they performed an abdominocentesis and fluid analysis. The total nucleated cell count was markedly elevated and comprised mostly of variably degenerate neutrophils, some of which had intracellular rod-shaped bacteria.  See images of Mac’s fluid here

Diagnosis and Treatment

Mac had presented with an acute abdomen, anorexic, lethargic, and in a lot of pain. A septic focus was found in his abdomen, likely some compromise of the GI tract. He had an irregular spleen and a mastocytemia, which may or may not have been a non-specific inflammatory response or neoplastic, but necessitated further investigation.

• The compromise of the GI tract that allowed translocation into the abdominal cavity had to be fixed. Surgery would provide an opportunity to assess the GI tract as well as look at the spleen. Mac was placed on fluids and pain control, anesthetized, and then prepped for surgery.
  • Surgical Findings: The spleen, full of bumpy nodules, was removed. The surgical team also found the source of the septic peritonitis; Mac had a perforation near his pylorus.
• When looking at a tissue scraping and stained cytologic preparation of one of the splenic nodules under the microscope, the pathologist recognized wall-to-wall mast cells.
• Pathology Findings:
  • Mac had splenic (or possibly visceral) mast cell neoplasia, which is how the mast cells got into circulation.
  • Histopathology from the tissue in the area of the gastric perforation diagnosed a suspected deep ulcer that perforated the wall of the pylorus. Presumably, the innumerable neoplastic mast cells resulted in increased histamine release, with a resulting perforating ulcer and septic peritonitis.
• After recovery from his laparotomy, splenectomy, and pyloric resection, Mac received two doses of chemotherapy for any residual neoplastic mast cells, and he completely recovered with no further mast cells detectable.

Case Impact

Even in the absence of a traditional inflammatory leukogram characterized by a leukocytosis (increased total white cell count) and neutrophilia (increased total neutrophil count), the presence of bands serve as the hallmark of inflammatory disease. An abnormal WBC scattergram and morphology flags can provide additional clues beyond the numerical CBC data to recognize significant inflammatory disease.

In Mac’s case, blood film review confirmed the suspected toxic bands and additionally identified his mastocytemia. Effusion analysis additionally identified the septic exudate, prompting the team to take him to surgery. So, the biggest takeaway from Mac’s case is this: you won’t know unless you look.