Nonleukemic Lymphocytosis 147 



The significance of absolute values can only be interpreted in the light of 

 established normals. The number of circulating lymphocytes per cubic 

 millimeter of blood varies at different ages and thus different normal 

 values can be established for various age groups (Fig. 11-1). In accordance 

 with these normal values, absolute lymphocytosis occurs when there are 

 more than 4000 lymphocytes per cubic millimeter of blood in adults, 

 7000 per cubic millimeter in children, or 9000 per cubic millimeter in in- 

 fants and young children. 



CONDITIONS ACCOMPANIED BY LYMPHOCYTOSIS 



The conditions which are accompanied by (nonleukemic) lymphocytosis 

 can be classified in two general groups (Table 11-1). In Group I are diseases 

 in which lymphocytosis is either so characteristic in type or so constant in 

 occurrence as to have diagnostic importance. In Group II are diseases that 

 may, at some stage, show lymphocytosis, but this is transient, inconstant, and 

 by itself not particularly diagnostic. 



The lymphocytic responses which accompany the conditions listed in 

 Group II are seldom striking in degree. II one follows carefully the 

 peripheral blood picture in hospital patients, it is not uncommon to en- 

 counter transient lymphocytosis in a great variety of diseases. It was felt 

 at one time that the lymphocytosis seen during the recovery phase of 

 many infectious diseases is of prognostic significance. Although much 

 was made of this in the older literature, it is my feeling that one can no 

 longer attach much significance to this change. This is not to negate the 

 older findings. Rather, the course of infectious diseases has been markedly 

 altered in the last 20 years by the use of antibiotics, with altered responses 

 and accelerated recoveries, so that one depends on more reliable criteria 

 to determine prognosis and the course of a disease. 



Turning then to Group I, it is apparent that these diseases have either 

 a proved or almost certain viral etiology. It seems to me that there is some 

 merit in further dividing this first group into two subgroups. Subgroup I-A 

 is headed by infectious mononucleosis and is composed of viral diseases 

 in which the peripheral blood smear shows "atypical lymphocytes." We 

 have called these atypical lymphocytes "virocytes" in accordance with the 

 suggestion made by Litwins and Lebowitz. 12 Subgroup I-B is characterized 

 by the appearance in the peripheral blood of a larger than normal number 

 of lymphocytes which generally are normal in appearance, usually of the 

 small type, and which do not have the morphologic features of virocytes. 

 I should like first to dispose of the second group by saying that lympho- 

 cytosis is a common and reliable feature of the peripheral blood in these 

 diseases. Although it does not aid in distinguishing between diseases by 



