What type of cells are often misidentified as protozoa in a patient with diarrhea?

In cases of diarrhea, the presence of certain cells in stool samples can lead to misidentification, particularly when the morphological characteristics of these cells resemble those of protozoa. Polymorphonuclear leukocytes (PMNs), also known as neutrophils, are a type of white blood cell that plays an essential role in the body's immune response, especially during infections.

When a patient has diarrhea, particularly due to an infectious cause, the body responds by sending PMNs to the site of inflammation or infection in the gastrointestinal tract. These cells can sometimes be seen in stool samples and have a multi-lobed nucleus and granular cytoplasm that can be confusingly similar to some protozoan organisms, especially in stained preparations under a microscope. Therefore, the misidentification can occur, as both PMNs and protozoa can present in similar shapes or sizes, especially when viewed hastily.

Recognizing PMNs as often misidentified as protozoa underscores the importance of careful microscopy and differentiation based on specific characteristics to avoid diagnostic errors and ensure appropriate treatment for the patient.