I word-searched the autopsies. Two of them, Rustem and Aleksander, make no mention of the spleen, and where Igor's is mentioned it's said to be have been small.
Normal average spleen size is 5 x 3 x 1.5 inches (12.7cm x 7.62cm x 3.75cm). Women have smaller spleens, and taller people bigger. With the exception of Yuri D's 1cm spleen thickness, which must be a typo/mistranslation, the other 5 measured spleens fall within normal parameters.
One thing which can cause the spleen to shrink is pneumococcal infection, if it gets into the bloodstream.
Yuri D
The spleen is flabby to the touch, the capsule is wrinkled, the size of the spleen is 1 x 7 x 3 cm, the tissue of its dark-cherry color on the incisions, the pulp gives a slight scraping from the surface of the incision.
Yuri K
The spleen is 9 x 6 x 3 in size. When sectioned the tissue of the spleen is dark red in color. The spleen is limp and its capsule is shriveled, and pulp is released with heavy scraping.
Igor
The spleen is small lobular when sectioned and of purple-red color.
Zina
The spleen is limp when palpated and its capsule is shriveled. When sectioned, the tissue of the spleen is dark cherry in color. The slurry from the surface of the section is given with much scraping. The size of the spleen is 9 x 6.2 x 2 cm
Lyuda
The spleen is flabby when palpated, and the channels are still wrinkled. The spleen size is 7 х 5 х 2 cm.
Semyon
The spleen is feeble during palpation. Its capsule is shrunk. The size of the spleen is 10 х 7 х 3 cm. The spleen tissue is of dark cherry color when sectioned.
Tibo
The spleen is flaccid when palpated, its capsule is shriveled, and is sized 9 x 5 x 3 cm. When sectioned, the tissue of the spleen had a dark red color and gave a thick pulp when scraped.