What does a skin tag look like under a microscope?

Microscopically, a skin tag looks like a small hanging pearl. Laboratory preparation of the tissue is required before looking at the skin tag under the microscope. The skin is stained with a stain called hematoxylin and eosin ("H&E"). Under the microscope, there is a colored spherical tissue attached to a small stalk. The purple outer layer (epidermis) overlies a pink core (dermis).

The outer layer of the skin (the epidermis) shows overgrowth (hyperplasia), and it encloses an underlying layer of skin (the dermis) in which the normally present collagen fibers appear abnormally loose and swollen. Usually there are no hairs, moles, or other skin structures present in skin tags.

While the majority of skin tags removed are discarded into special medical waste containers, sometimes tissue is sent for microscopic exam by a specialist doctor called a pathologist. Irregular skin growths that are larger, bleed, or have an unusual presentation may require pathology examination to make sure there are no irregular cells or skin cancers.

Some common conditions that can mimic skin tags include seborrheic keratosis, moles, warts, cysts, milia, neurofibromas, and nevus lipomatosus. Rarely, skin cancers like basal cell carcinoma, squamous cell carcinoma, and malignant melanoma may mimic skin tags.

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