Answer: A 23-year-old Peace Corps volunteer lived in a traditional mud hut with a thatched roof in a rural savannah village in Gambia
Medical Mystery: Painless Ulcers — The Answer
by Morris-Jones, S.
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PubMed Citation
To the Editor: The medical mystery in the April 1 issue1 involved a 23-year-old Peace Corps volunteer in Gambia. Painless ulcers developed on his lower legs (Figure 1A) and did not respond to local or systemic antimicrobial therapy.
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Figure 1. Leishmania in a Peace Corps Volunteer.
Panel A shows a painless ulcer on the man's leg. Panel B shows leishmania amastigotes (arrows; Giemsa, x100). Panel C shows the phlebotomus sandfly, the vector of the parasite.
A slit-skin smear from the margin of the ulcer showed leishmania amastigotes (Figure 1B). Given the patient's geographic exposure, these parasites were Leishmania major. The main animal reservoirs for the protozoan in this geographic area are burrowing rodents, and the vector is the phlebotomus sandfly (Figure 1C). The lesions remain localized and usually heal spontaneously within one year, with scarring, although pentavalent antimonial compounds may accelerate recovery. The differential diagnosis includes tropical ulcer, usually painful and rapidly responsive to -lactam therapy, and Buruli ulcer, caused by Mycobacterium ulcerans. Buruli ulcers initially spread subcutaneously and therefore characteristically have undermined borders.
Stephen Morris-Jones, M.R.C.P.
Martin Weber, M.D.
Medical Research Council Laboratories
Fajara, Gambia
Editor's note: We received 861 responses to this medical mystery — 60 percent from physicians in practice, 20 percent from physicians in training, 16 percent from medical students, and 4 percent from other readers. Responses were received from 59 countries. Sixty percent correctly identified this condition as due to leishmania. Cutaneous leishmaniasis results from the bite of an infected sandfly, which produces a slow-healing skin ulcer. The most common alternative diagnosis was Buruli ulcer, caused by M. ulcerans, suggested by 20 percent. Treponemal infection was suggested by 6 percent, and pyoderma gangrenosum by 3 percent. Other suggested diagnoses include coining, spider bite, botryomycosis, nocardiosis, African histoplasmosis, leprosy, and tuberculosis. Many insightful comments and terms appeared in the responses, including "Avoid sandflies," "Baghdad boil," and "We have seen a lot of this in troops returning from Iraq." One respondent wrote, "Unlike the crocodile portrayed on the coin, the predator in this case gave up its tail several weeks before the photo was taken. The patient has Old World cutaneous leishmaniasis — the Rose of Jericho."
References
1. Morris-Jones S, Weber M. A medical mystery -- painless ulcers. N Engl J Med 2004;350:1442-1442.[Full Text]
