WARNING: GRAPHIC IMAGE BELOW

A woman with a family history of head cysts grew emotional while explaining to a celebrity dermatologist that for the past year, one of the growths had been developing into a “horn” on the back of her head.

In an exclusive clip of TLC’s “Dr. Pimple Popper” shared with Fox News ahead of Thursday’s episode, patient “Lisa” explains that the growth started about a year ago when one of the cysts burst.

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“I have a horn growing out of my head,” she told Dr. Sandra Lee, better known as “Dr. Pimple Popper.”

The growth, described by Lisa as a "horn," had been developing for over a year. (TLC )

Lisa pointed to other smaller growths near her ear, and revealed that she has a family history of head cysts and that her mother used to call them “wens.” Lee explains that the growths are called pilar cysts, which occur in less than 10 percent of the population, but are the most common cysts that affect the scalp.

According to the National Center for Biotechnology Information, pilar cysts typically present as flesh-colored growths, and it’s not unusual for a patient to have inherited the condition. While they can be slow-growing, those with rapid change in size may indicate infection or malignancy.

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The cysts may cause pain, and a patient may experience complications such as inflammation, cosmetic disfigurements, infection and calcification. Treatment can include surgical removal or radiotherapy and chemotherapy in the case of malignant growth.

But in Lisa’s case, the trouble began about a year ago when one of the cysts burst, and she “squeezed it and it came to a point where I couldn’t squeeze it anymore, and then this started growing.”

Lee parts Lisa’s hair to reveal a cutaneous horn, or as she describes it, “a fingernail that’s gone crazy.”

“I’ve seen cutaneous horns before but certainly this is the largest cutaneous horn that I’ve ever seen,” Lee said. “One of the things that I’m certainly thinking about with Lisa here is skin cancer because one type of squamous cell carcinoma called a keratoacanthoma can look like this.”

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Keratoacanthoma is a relatively common growth often associated with previous trauma or injury, but can be difficult to tell apart from squamous cell carcinomas, according to the American Osteopathic College of Dermatology.

Lee told Lisa that she wasn’t “exactly sure” what it is, but suspects a pilar cyst that’s grown out of control based on her family history.

Lisa’s episode airs Thursday a 9 p.m. ET.