Epithelial Cells On Dog SkinUpdated 8 months ago

There are two types of skin cells commonly seen under the microscope (1000x magnification) on a skin swab sample cytology: corneocytes and keratinocytes. 

Corneocytes are “dead skin flakes” on the surface layer of skin which flake off as they’re replaced by newer, deeper layers of skin cells. Keratinocytes are living skin cells (with a nucleus), found just underneath the corneocytes in the skin layer. So, it’s common and quite normal to find small (occasional) numbers of each under the microscope. This is especially true for corneocytes, while less so for keratinocytes. This is because an ear swab sample should only wipe off low numbers of corneocytes and even fewer numbers of the deeper keratinocytes if the skin of the ear is healthy.

 Larger quantities of both types of skin cells are common if the skin is inflamed (red, sore, swollen) and/or if a microbe (bacteria, yeast) infection or skin mite infestation is underway. A third, less common skin cell found on swab cytology is the melanocyte. These are pigmented cells of the deeper skin layer, located alongside the keratinocytes. They produce melanin, a brown to black natural pigment that gives skin and hair color. When melanocytes are found on skin swab cytology, this skin area should get examined by a veterinarian since these skin cells are also a common form of skin cancer. Melanocytomas (most common) are benign melanocyte tumors of the skin that are often more easily treatable/curable than the more aggressive malignant melanomas (more common in schnauzers and Scottish Terriers). 

It’s important to interpret the skin cell results along with the other cytology results for the same skin area. If the skin cell counts are high (1+, 2+, 3+, 4+) in your dog’s skin swab samples (if even occasional melanocytes), combined with high numbers of bacteria and/or yeast (or any ear mites), and/or with one or more clinical signs (e.g., scratching or chewing at the swabbed area), then a physical exam of your dog’s skin is needed by a veterinarian.

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