Thursday, March 06, 2003
(no, this is not a misprint)
Recently I had a new patient come in complaining of some unspecified gastroenterologic problem. I work with a resident twice a week; that afternoon she happened to be there, so I sent her in to evaluate the patient.
She came back looking green. "She says she's got worms!"
"What exactly did she tell you about her symptoms?" I asked. This elicited a lurid story -- hold on to your gorge -- of the patient feeling worms crawling in her abdomen, seeing worms in her stool, and having some sort of rectal blister that burst "and worms came out."
The reason I'm going into such detail is this: I knew this couldn't be true. Parasites do not behave like that, at least not the types most likely to be picked up in North America. Also, with symptoms like that she'd had to have had a huge parasite load - she would have been really sick and possibly developed an abdominal obstruction. (As a side note, I was once privileged to see an upper GI X-ray of a patient from the Third World who presented with symptoms of abdominal obstruction; the study showed a mass in the small intestine which turned out to be a worm ball. Ugh.) Taking advantage of our computer system, which taps into the local medical center, I saw that she had had a stool study for parasites within the last few months... negative. With the symptoms she was describing, that would have been almost impossible.
Back to the resident. I explained to her that I found this story highly suspicious, told her why, and sent her in there to gather additional information: "Does she have a travel history? How big were the worms? How many were there? What did her previous doctor say? Push for as much detail as you can and watch how she reacts."
I already had my suspected diagnosis: formication. This isn't a common phenomenon, but it is well-known and seen most often in patients taking drugs (it's also referred to as "coke bugs"). However, it is also seen in patients who don't take drugs... usually the elderly. It's felt to be a manifestation of mild psychosis. The patients are preoccupied with the idea that they have parasites in their body, usually under the skin, and often present with abrasions or excoriations on their skin where they've dug into themselves trying to get the "worms" out.
My resident came back and reported that the more questions she asked, the more evasive the patient got. Diagnosis confirmed - or almost. I went in, evaluated the patient and elicited much the same history, did an exam and found nothing. She did look to have a local dermatitis in the area, possibly fungal, so I gave her some cream, explained what I thought was likely to be going on, pointed out that she had a recent negative stool study and asked her to follow up in a few weeks. So far, no follow-up, but we shall see.