“…The causative drugs include PAS [4,11], hydantoin anticonvulsants [6,8,13,16], phenylbutazone [10], and carbamazepin [14]. In some cases, the large numbers of atypical mononuclear cells in conjunction with lymph node enlargement have led to confusion with infectious mononucleosis [11] and even with malig nant lymphomas [12].…”