Protean Mononucleosis

To the Editor.—  "From the clinical standpoint the most impressive features of infectious mononucleosis are its protean manifestations." This is from my article reporting the first autopsied case.¹ I assume full blame for starting the use of "protean." Numerous subsequent authors have repeated the term, often copying the sentence.I cannot agree with the somewhat confused letter of Dr. Dirckx (226:79, 1973) in which he infers that the heterophil titer must be positive 1:28 or higher to confirm a diagnosis, and that reported cases with lower titers and low blood counts are to be questioned.There is no single test, examination, or symptom that can be used to confirm or disprove the diagnosis. The total picture, all the evidence, and the good judgment and experience of the physician are needed in diagnosing this disease that is, indeed, protean. The outcome in a particular patient is important, the prognosis is