280 The Lymphocyte and Lymphocytic Tissue 



unimportant feature in distinguishing these cells from immature lympho- 

 cytes. Attention must be paid to the nuclear pattern in which large, coarse, 

 dark-purple chromatin blocks blend imperceptibly with the colorless or 

 light-blue parachromatin (periphery of Figs. 19-1, 19-2, 19-18). There is little 

 or no chromatin-parachromatin distinction, although larger amounts of 

 parachromatin are present in the nuclei of the larger mature lymphocytes. 

 Nucleoli are completely masked, but too much pressure applied in imprint- 



Fig. 19-16. Leukemic adult lymphocytes from the blood in a case of 

 chronic lymphocytic leukemia. Note bizarre nuclear indentations 

 which may connote malignancy but do not identify degree of dif- 

 ferentiation since similar bizarre nuclear configurations are present 

 in the reticulum cells of Fig. 19-4 and the prolymphocytes of Figs. 

 19-14 and 19-15. Leishman stain, (x 1100) 



ing lymphocytic tissues or in making blood smears will readily unmask the 

 nucleoli present in even mature lymphocytes. The nuclear membrane is 

 thick and heavy. Normally, even in the larger adult forms, there is only a 

 narrow or moderate band of pale to dark-blue cytoplasm. Large amounts of 

 cytoplasm immediately place the mature cells into the class of atypical 

 lymphocytes (see below). Round, red, relatively large, btit sparse azurophilic 

 granules may or may not be present. Normal, mature lymphocytes may 

 present some nuclear indentation, although extreme degrees of nuclear 

 lobulation suggest atypism or even malignancy. 



Malignancies of mature lymphocytes include diffuse lymphosarcoma of 

 the lymphocytic type, giant follicular lymphoma of the lymphocytic cell 



