Family Practice News

December 1, 2002
Volume 32
Number 23
History is important
Detective Work Helps Identify Cause of Rash


Sherry Boschert
San Francisco Bureau
To diagnose the cause of rash on the palms and soles of the feet in systemically ill patients, think like a news reporter.
Every journalist learns to ask about the "four W's": who, what, when, and where. These four W's also comprise what Dr. William J. Barson calls an epidemiology history that provides an alternative avenue for diagnosing the infectious diseases behind dermatologic problems, including rashes of the palms and soles.
"With infectious diseases, there are a number of ways one can approach the problem. It's not just considering the signs and symptoms the patient is having, but also looking at the epidemiology," said Dr. Barson of Ohio State University and a member of the section on infectious diseases at Children's Hospital in Columbus.
Ask the following questions to speed your diagnosis, he suggested in an interview:
Who has the patient been with? Besides asking about contacts with local people, extend the travel history to ask whether a visitor from someplace
else may have brought the patient in contact with infectious organisms.
What has the patient been doing? Leisure activities such as swimming, boating, and hiking naturally come to mind. In teenagers, ask also about
work activities and sexual contacts.
When is the problem happening? Many infectious diseases have a seasonal distribution.
Where has the patient been? Think locally and globally. Has the patient
been away from usual territory-traveled out of state or to a foreign
country?
There are not many things that cause a rash on the palms and soles, so it's worth committing them to memory, he added.
Infectious etiologies can be bacterial, viral, or the parasite Toxoplasma gondii. There also are several noninfectious causes. Also, any microorganism that causes endocarditis or septic thrombophlebitis may produce lesions on
the palms and soles.
Bacterial etiologies. Group A streptococcus or Staphylococcus aureus
usually don't cause individual, discrete lesions on the palms and soles but can generate erythema there when they're the toxin-producing versions responsible for toxic shock syndrome.
Think also of disseminated disease from two Neisseria organisms-gonorrhoeae and meningitidis. Disseminated gonorrhoeae can produce a variety of lesion types on the hands, feet, fingers, and toes, such as pustular lesions or erythematous vesicular lesions. With meningococcal disease, you may see the redness of petechiae that does not blanch when you put pressure on them, or darker, black areas where the tissue has infarcted and died.
Streptobacillus moniliformis is the root of a rare cause of rashes on the palms and soles: rat bite fever. Dr. Barson has seen just one case in his career-in a teenage boy who had fever, arthritis, and pustularlike lesions
on a couple of fingers. He had numerous animal contacts, including a pet
rat.
Initially, Dr. Barson thought this was gonococcal infection and asked the
lab to add gelatin to the blood culture bottles to eliminate the known inhibitory effect of the anticoagulant, sodium polyanethol sulfonate (SPS), which is present in the blood culture media.
Instead of growing the gram-negative diplococci typical of Neisseria,
however, the cultures showed the gram-negative rods of S. moniliformis. Dr. Barson subsequently learned that SPS also inhibits the growth of S. moniliformis.
Contact with soil or water contaminated by an animal's Leptospira-containing urine may cause leptospirosis that produces a rash on the palms or soles.
The spirochetes that cause Lyme disease (Borrelia burgdorferi) or syphilis (Treponema pallidum) may be the culprits in rashes on the palms or the
soles.
The initial solitary, erythema migrans lesion of Lyme disease can give way
to multiple "daughter" lesions with disseminated disease.
The Rickettsia species cause Rocky Mountain spotted fever, with a rash that typically starts on the wrists and ankles before spreading centrally and to the palms and soles. Less commonly, a rash may accompany Ehrlichia
infection, which can look much like Rocky Mountain spotted fever.
Viral etiologies. Most of the herpes viruses-herpes simplex,
cytomegalovirus, Epstein-Barr, and varicella-zoster-can produce lesions on
the palms and soles.
These may present as papular purpuric gloves and socks syndrome, in which a rash occurs on the hands and feet. The etiologies suggested are parvovirus B19, coxsackievirus B6, measles, Epstein-Barr virus, cytomegalovirus, human herpesvirus 6, hepatitis B, and mercury intoxication.
Adenovirus, enteroviruses, and less common problems such as rubella,
rubeola, and dengue virus also can present as a rash on the palms and soles, he commented.
If the rash occurs on hands and feet in the summertime, and the child is not too ill and also has lesions in the mouth, it's a good bet that this is the "hand-foot-mouth disease" of enteroviruses, Dr. Barson commented.
Noninfectious etiologies. The rash may be due to one of several vasculitic disorders-systemic lupus erythematosus, Kawasaki disease, or
dermatomyositis. More commonly, a rash due to a noninfectious source is
caused by drug reactions from amoxicillin, sulfonamides, or anticonvulsants. Stevens-Johnson syndrome generates a specific erythema multiforme-type rash with involvement of the mucous membranes in the mouth, eyes, genitalia, or rectum.
Dr. Barson said that asking questions about work activities provided the
clue to a rare cause of rash on the palms and soles in one teenage boy who also had fever, sweating, tachycardia, hypertension, and emotional instability. The boy worked on a salvage crew cleaning up after factory
spills and had developed mercury poisoning.
"It's easy to gloss over the palms and soles. The majority of the time, there's nothing there, but when you do find a rash on the palms and soles,
it should bring to mind this differential diagnosis," Dr. Barson said. Copyright © 2002 by International Medical News Group

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