Correspondence

Medical Mystery: The Answer

N Engl J Med 2000; 343:1573November 23, 2000

Article

To the Editor:

The medical mystery in the October 5 issue1 involved a 19-year-old man, shown here in Figure 1Figure 1Photographs of the Iris of a 19-Year-Old Man with Neurofibromatosis Type 1, Showing Multiple Lisch Nodules., who had numerous dome-shaped elevations on the surface of the iris, or Lisch nodules. Lisch nodules are melanocytic hamartomas that are either yellow or brown. They are visible on inspection, pathognomonic of neurofibromatosis type 1, and do not cause symptoms. The incidence of Lisch nodules among patients with neurofibromatosis type 1 increases with age: at the age of 5 years only 22 percent have Lisch nodules, whereas at the age of 20 years 100 percent have them.2 Therefore, older patients who do not have Lisch nodules are also unlikely to have neurofibromatosis type 1.

Gerhard Kurlemann, M.D.
Otfried Debus, M.D.
University of Münster, D-48129 Münster, Germany

2 References

1. 1

   Kurlemann G, Debus O. A medical mystery. N Engl J Med 2000;343:1019-1019
   Full Text | Web of Science | Medline

2. 2

   Lubs M-LE, Bauer MS, Formas ME, Djokic B. Lisch nodules in neurofibromatosis type 1. N Engl J Med 1991;324:1264-1266
   Full Text | Web of Science | Medline