Splenic alterations in hairy cell leukemia

Spleens from 12 patients with hairy cell leukemia were studied for morphologic alterations. Paraffin-embedded, plastic-embedded, and fresh-frozen tissue sections were stained for a variety of histochemical reactions. Hairy cells were present in great numbers within the splenic sinuses and cords. Hairy cells adhered to splenic endothelial lining cells, other hairy cells, and erythrocytes. Large clumps of hairy cells filled and partially occluded splenic sinuses. Numerous dilated sinuses, abnormal sinuses, and blood-filled spaces were present in all cases. Ring fibers around abnormal sinuses were fragmented and reduced in amount. Occasionally, the number of reticular fibers appeared increased around abnormal sinuses, but, in general, it was decreased in areas around the blood-filled spaces and in splenic cords markedly infiltrated by hairy cells. The formation of abnormal sinuses and blood-filled spaces probably resulted from the obstruction of venous blood flow and from injury or death of endothelial lining cells.