Diagnostic dilemma: A rash 'migrated' across a man's body from his anus

The symptoms: The patient, who had previously been diagnosed with lung cancer, had been hospitalized because the cancer had spread and was pressing on his spinal cord. During treatment, he was given a high dose of glucocorticoids, which reduce inflammation and are sometimes used as part of cancer treatment or to counter chemotherapy side effects. But after four days, the man developed an itchy rash and mild diarrhea. What happened next: Doctors examined the rash, which looked like red, wavy lines all over the patient's body. The clinicians found that...