The Strange Disease That Turns Humans into Unicorns: The 'Cutaneous Horn' Explained

Figure 1. A wax recreation of Madame Dimanche featuring her 10-inch-long cutaneous horn.Photo byallthatsinteresting.com.

Mythology has long been populated with creatures bearing horns—unicorns, devils, and even the elusive jackalope. While these fantastical beings are the stuff of legend, they may have roots in a very real medical phenomenon. The condition in question? A bizarre skin growth is known as a cutaneous horn.

At its core, a cutaneous horn is exactly as it sounds: a protrusion resembling a horn that emerges from the skin. While it's common to associate horns with animals like deer or goats, these growths can occur in humans, often leading to unsettling results.

In fact, cutaneous horns are more frequently found in humans than in other animals, lending an eerie and tangible dimension to tales of horned creatures.

What Exactly Is a Cutaneous Horn?

A cutaneous horn typically forms due to a tumor in the skin, resulting from an excess buildup of keratin—the protein responsible for creating hair, skin, and nails.

This keratin accumulates, hardens, and eventually juts out from the skin in the shape of a horn. While most skin tumors are more ordinary in appearance, cutaneous horns stand out for their distinct, conical shape, making them resemble miniature antlers.

Though these growths usually remain small, only a few centimeters in length, there have been cases where they grow to astonishing sizes.

The Remarkable Case of Madame Dimanche

One of the most well-known instances of a cutaneous horn occurred in Paris during the early 1800s. A widow named Madame Dimanche developed a horn in the middle of her forehead when she was 76 years old. Over the course of six years, the horn continued to grow until it eventually reached an astonishing 10 inches in length.

Despite initial advice that the horn posed no serious health risks, it eventually became a significant nuisance, obstructing her daily life. When Madame Dimanche finally opted for surgery, the horn had extended so far that it nearly touched her chin. A wax recreation of her condition still exists today, immortalizing this extraordinary case (Figure 1).

More recent cases of cutaneous horn include:

• 2007: Ma Zhong Nan, a 93-year-old elderly man in China.
• 2011: 84-year-old White man in London, the UK.
• 2015: Liang Xiuzhen, an 87-year-old elderly woman in Sichuan, China.
• 2019: Shyam Lal Yadav, a 74-year-old farmer in India.
• 2023: 34-year-old South-Asian male in Dubai.

Shyam Lal Yadav, 74, with cutaneous horn.Photo bymetro.co.

The Mystery Behind Cutaneous Horns

Despite their unsettling appearance, cutaneous horns are generally not life-threatening. They typically appear in areas of the skin that are frequently exposed to sunlight, such as the face, ears, and hands. Given this, some researchers theorize that ultraviolet radiation could play a role in their formation.

In addition to sunlight exposure, some experts believe there may be a connection between cutaneous horns and the human papillomavirus (HPV). Certain strains of HPV cause abnormal growths on the skin, such as the bark-like formations seen in a condition known as "tree-man syndrome."

These growths share a similar keratin makeup with cutaneous horns. Intriguingly, there is also a strain of papillomavirus that affects rabbits, causing them to grow horn-like projections, which could further hint at a viral link in humans.

Are Cutaneous Horns Dangerous?

In about 20% of cases, cutaneous horns can signal an underlying skin condition, such as carcinoma, a type of skin cancer. But the vast majority of horns are benign. While they can be unsightly and occasionally interfere with daily activities, they are typically harmless and easily removed with minor surgery.

A Link to Myths and Legends?

It's not difficult to see how cutaneous horns might have fueled ancient tales of mythical beings. A person with a significant horn growth on their head could easily have been mistaken for a creature out of legend, perhaps inspiring the stories of unicorns, devils, or other horned entities.

Cutaneous horns serve as a fascinating example of how medical anomalies can blur the lines between fact and fiction, reminding us that sometimes, the truth is stranger than myth.