While the various potential signs and symptoms of rosacea may mimic a variety of other disorders from acne to lupus erythematosus, an accurate diagnosis may be especially important to rule out the possibility of carcinoid syndrome, a rare cancer caused by a tumor that is often curable if detected early but may be fatal if left untreated.

"A very rare disorder, carcinoid produces flushing and visible blood vessels that are also common to rosacea," said Dr. Joseph Bikowski, clinical assistant professor of dermatology at The Ohio State University. "However, while they often appear on the face, with carcinoid syndrome these symptoms also may extend over the entire body and be accompanied by other manifestations such as diarrhea, abdominal cramping and swelling of the ankles, legs, hands and arms."

Caused by carcinoid tumors that damage organs, carcinoid syndrome is estimated to occur in only 20 to 40 individuals per one million in the U.S. Individuals with carcinoid syndrome may be at significantly greater risk of death than those with tumors alone because the damage is a consequence of the excessive amounts of potent hormones released into the circulation, rather than the size or spread of the tumors themselves.

"Carcinoid may not always be considered because of its rarity," Dr. Bikowski said. "Anyone who may have signs and symptoms of carcinoid should see their doctor."