Cytochemistry of the Lymphocytes 33 



Lymphoblastic Leukemia. True lymphoblastic leukemia is an extremely 

 rare entity and differs from lymphosarcoma and leukolymphosarcoma with 

 which it has been frequently confused. The cells observed in lymphoblastic 

 leukemia (Figs. 3-17, 3-18) are rather large (14-18 p) , round or oval cells 

 with large, round, moderately vesicular nuclei, a prominent nuclear mem- 

 brane, and one to three large prominent nucleoli. Mitochondria are numer- 

 ous and appear considerably larger than those seen in lymphocytic leukemia 

 or lymphosarcoma. The mitochondria localize near the nuclear hof and in 

 the more distal part of the cytoplasm. Neutral red staining granules or 

 vacuoles localize near the cytocentrum and stain an orange-red color. These 

 cells exhibit slight hand-mirror type motility characteristic of lymphoid cells. 



Lymphosarcoma. The pathologic lymphoid cells characterizing lympho- 

 sarcoma in lymphatic tissue and in the blood (so-called leukolymphosar- 

 coma) are morphologic all) identical; however, these cells may exhibit con- 

 siderable variation in morphology (Figs. 3-12 through 3-16) . The classic 

 lymphoid cells present in lymphosarcoma appear rather small but actually 

 are slightly larger (12-14 /U ) than the normal small lymphocytes and those 

 of lymphocytic leukemia. The lymphosarcoma cells possess a vesicular 

 nucleus with a thin nuclear membrane, several prominent nucleoli, and a 

 small rim of opaque, moderately basophilic cytoplasm. Not infrequently 

 the nuclei of the lymphosarcoma cells appear hyperchromatic (Fig. 3-12) , 

 become markedly indented, and may assume a lobed or clover-leaf nuclear 

 form. It is possible that these changes could be correlated with the increased 

 content of DNA which has been observed in the cells of lymphosarcoma. 80 

 The small spherical mitochondria tend to localize near the nuclear hof, and 

 a small number of granules which stain orange-red with neutral red occur 

 near the region of the cytocentrum. Highly retractile, nonstaining lipoid 

 droplets may occur in variable numbers in the cytoplasm of the lympho- 

 sarcoma cells in certain patients with this disease. The lymphoid cells of 

 lymphosarcoma have a relatively high mitotic index in contrast to those of 

 lymphocytic and lymphoblastic leukemia. A comparison of the morphologic 

 structure of the cells of lymphosarcoma reveals that they exhibit relatively 

 few characteristics in common with lymphoblasts seen in normal lymphatic- 

 tissue. 



Occasionally in certain patients with lymphosarcoma, a number of cells 

 exhibit considerable variations in si/e with slight variations in the relative 

 amount of cytoplasm, cytoplasmic basophilia, and in the number of mito- 

 chondria. These observations suggest a maturation series in the cells of 

 lymphosarcoma since small, medium, and large forms (Fig. 3-15) can be 

 distinguished. 



