They are conditions that have not made an indelible mark in the tomes of medicine.
Bring them up in front of a physician and in some cases you may get little more than a blank stare.
But they exist, sometimes as a rare disorder, sometimes as a disorder that falls between many medical specialties, and sometimes as an extreme form of a normal bodily function that most people experience every day.
And while the thought of a giant port-wine stain or uncontrollable hiccups are cocktail-party fodder for some, they can be a source of difficulty and shame for those who experience them firsthand.
Sometimes there are cures for what ails them but most often people with these strange conditions must move forward with their lives, coping with physical, social and emotional discomfort, because there is no cure.
The following pages feature some of the more unusual medical conditions that have received recent media attention.
If she dresses carefully and positions herself properly, Carla Sosenko, 32 from Brooklyn, N.Y., knows no one will be able to see any of the physical flaws that she works hard to conceal.
But, unlike the bumps and bulges that many people would like to hide, Sosenko's are the result of a rare congenital disorder called Klippel-Trenaunay Syndrome (KTS).
"It was always about my appearance, which is, in a lot of ways, fortunate," Sosenko said. "In terms of the medical issues, I never felt like I had them."
Symptoms can vary widely and, depending on the severity of the condition, can include pain, blood clots, seizures, blindness and mental retardation. Excessive bone growth can lead to amputation of the enlarged limb.
Because KTS falls between specialties -- vascular, orthopedic and lymphatic -- the disorder was often misdiagnosed and treated inappropriately.
"There is tremendous confusion [about KTS]," said Dr. John Mulliken, co-director of Vascular Anomalies Center at Children's Hospital Boston. "These patients used to be medical nomads. No one doctor can take care of these patients."
Sosenko's right leg is slightly larger than her left, her back is uneven with fat deposits, and a plum-colored mark from enlarged blood vessels under the skin, called a port-wine stain, stretches from her torso to her right thigh.
Sosenko said that many people she meets might not notice her lumpy back or that she drags her right leg slightly when she walks. Others might notice and not comment and still others might ask her about it.
"If a perfect stranger says something cruel, it hurts," Sosenko said. "That will hurt no matter how much progress I make, no matter how confident I feel."
Still, Sosenko admitted that the varicose veins that she has can hurt and excessive walking can be taxing because of the length difference between her legs.
Fortunately, Sosenko's condition is not painful nor has it prevented her from any of her favorite activities, such as yoga.
"It's discomfort, it's not debiblitating," Sosenko said.
Christopher Sands, 25, has been battling hiccups, normally a mundane, short-lived biological function, for more than two years.