A Diagnostic Dilemma

I have permission from a friend to tell you this story and to display his picture. Last week he informed me that he was suffering low grade fever, chills, sweating, and fatigue. He said that he had muscle spasms, particularly of his back, and that someone had noticed a large red oblong mark on his back near his left shoulder blade. According to my friend, the reddened skin was expanding in dimensions and was warm and tender to the touch. When my friend first called, I was far away from him and busy on the football field acting as a team doctor, so I instructed him to seek care in an emergency department close to his home.

The next morning, I checked in with him, and he informed me that the doctor who treated him in the E.D. felt that my friend had possibly incurred a spider bite, perhaps during his activities at a plant nursery. Furthermore, to the doctor, it looked like a possible “brown recluse spider” bite. These are known to be nasty bites that can cause a great deal of tissue destruction at the site of the bite. I know that many spiders use venom to subdue their prey, and the bites of many species can cause dramatic skin reactions. However, true brown recluse spiders are not indigenous to northern California. They only arrive here if they have hitched a ride on imported (to California) fruit or plants. So, I felt it best to see my friend as soon as possible.

The picture above is what I saw. The rash on his back was a large, raised, red patch with a small entry point (probable bite site) at the top. The entry point was pale grey in color and had a small clear blister in the middle, but no blood in the blister or obvious blackened tissue destruction, such as one would see with a brown recluse bite. It may have well been a spider bite, but I highly doubt that it was from a brown recluse spider or even from one of the more problematic species, like Tegenaria agrestis, found in the Pacific Northwest. The situation might have represented a skin infection from Streptococcus bacteria or even an atypical presentation (a rash known as erythema migrans) of early Lyme disease from the bite of a nymphal tick. So, in addition to the antibiotics my friend had been prescribed the night before, I added another antibiotic to cover Lyme disease. Two days later, the rash had faded and regressed in size considerably, and his other symptoms were nearly gone.

So, what did he have? Perhaps a spider bite reaction complicated by a skin infection. Possibly Lyme disease. We won’t know until we learn the results of some blood tests, but even then, we may not find out, because these tests are imperfect from a diagnostic standpoint. The important thing is that he got better, which is often the case in wilderness medicine. Sometimes, health care professionals and patients need to make an educated guess, and hope that treatment is effective.

Read the update on this case: "A Diagnostic Dilemma" Update

Tags: spider bite, brown recluse spider, spider, skin rash, Lyme disease, medical, physician, health, wilderness medicine, outdoor medicine, healthline

photo by Paul Auerbach