A Zebra is a rare diagnosis that is part of the differential diagnosis, but it should not be the immediate first answer in the diagnostic process.
When you hear hoofbeats, think of horses, not zebras.
Your next patient has Waldenström Macroglobulinemia? A Google search via Safari on the iPhone yields hits at cancer.gov and Wikipedia.
What about the medical suites?
Epocrates – No entry.
Pepid – No entry.
Skyscape – Yes, a detailed entry.
A low grade lymphoid malignancy which produces monoclonal IgM….
