Question: Please send me anything on erythema nodosum. My daughter had this during her pregnancy and is still having some problems. I think it is some kind of blood vessel disease. I would like to know how it affects your lungs. The doctor did not want to take chest X-rays. From what I've read, it does not appear to be a serious illness.

- L.D.

Answer: Readers will recall my earlier discussions of erythema nodosum, a condition marked by hot and painful skin nodules on the lower legs. Yes, the blood vessels within the nodules are inflamed. I discussed earlier a typical experience, that is of the patient who recovers uneventfully after a month or so - with no surprises. That's true of about 70 percent of cases. However, in a few it will last longer, and in fewer still may become chronic. Nature's rules are there to be defied, and so nothing in medicine is set in concrete.

Your daughter's case was unusual by virtue of her pregnancy alone. The reason for all the testing (another part of your letter) was to determine if the skin problem represented another disease process, something that can trigger it. Strep infection comes to mind. Drugs can cause it and so can illnesses like sarcoidosis (lungs) and ulcerative colitis. The doctor ruled out chest/lung X-rays in deference to your daughter's pregnant state. And incidentally, pregnancy itself has been associated with erythema nodosum.

Normally, anti-inflammation drugs will control erythema nodosum, and sometimes elastic stockings help. In truly serious cases, where the symptoms last for a long, long time, cortisone drugs may be brought into the picture.

Question: I am 20 and have never had an acne problem per se. However, I notice that when I have been exercising in my basement, wearing sweats, I get some acne. My basement is extra dusty. Is there a connection?

- Ms. K.T.

Answer: Humidity can cause an acne flare-up, as can other environmental factors, like working with grease or wearing tight garments and straps. I doubt that the dustiness has much to do with it. You should be extra careful in cleaning yourself after a workout. The acne report offers some other hints. Other readers can order a copy by writing: Dr. Donohue - No. 39, Box 5539, Riverton, NJ 08077-5539. enclosing a long, stamped (52 cents) self-addressed envelope and $3.

Question: When I had vaginosis, my doctor gave me an antibiotic tablet. It worked well. A girlfriend of mine had vaginosis diagnosed by her doctor. He gave her an antibiotic cream to apply to the area. Which is best?

- Mrs. L.D.

Answer: Either mode of treatment seems OK, either cream or tablet. Either has been shown effective. But there are lots of vaginosis causes, so one should never assign bacteria, for example, as a cause of any specific vaginosis episode.

Question: Years ago, I went to the doctor for a checkup and he would look my fingernails over closely. My doctors since then have never done that, and I do now have deep ridges on my fingernails. Isn't that an indication of something?

- Mrs. A.R.

Answer: Narrow ridges running the length of the nails most often mean nothing more than a family trait. And they do become more pronounced with age.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him at P.O. Box 5539, Riverton, NJ 08077-5539.

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