Schüffner's Dots

SCHÜFFNER'S DOTS (Schüffner). Red blood cells infected with Plasmodium vivax swell sharply, become pale, and, as first shown by Mannaberg (1893), lose the homogeneity of their protoplasm, which seems to disintegrate into small particles. These changes in erythrocytes in malaria tertiana were described in detail in 1899 by Schüffner using blood smears fixed with 1% formalin and glycerin (5–10%) and stained with Böhmer's hematoxylin. According to the author's description, the erythrocyte protoplasm is dotted with greenish polymorphic granules, partly lying freely and partly connected to each other. The stippling appears in the erythrocyte protoplasm as the ring-form parasite develops (2–3 hours after the beginning of its development) in the form of dust-like granularity, which enlarges as the parasite grows, and is called Schüffner's dots. Schüffner believed that the stippling represented particles of the parasite's protoplasm that had separated during its amoeboid movement. This assumption was seemingly confirmed by the identical staining of the parasite's protoplasm and the stippling. Subsequently, Schüffner's dots were studied using preparations stained with Romanowsky's azure-eosin, in which they acquire a chromatin-red color. This gave Schaudinn grounds to assume that the malaria parasite absorbs easily digestible components of the erythrocyte protoplasm, which causes the precipitation of nuclear substance residues in the form of Schüffner's dots. Maurer denies the nuclear nature of Schüffner's dots; he believes that under the influence of the parasite's vital activity, the protoplasmic components of the erythrocyte precipitate. Nocht and Mayer hold the same view, believing that Schüffner's dots appear as a result of colloidal separation (Entmischung) and the precipitation of erythrocyte substance. Chatton sees in Schüffner's dots traces left by the pseudopodia of the moving parasite in the erythrocyte membrane. The number of erythrocytes with Schüffner's dots in malaria tertiana depends to a large extent on the fixation and staining of the blood smear. When staining a smear without prior fixation, Schüffner's dots are detected in all infected erythrocytes (Walterhöfer); at the same time, among the fine Schüffner's dots, authors occasionally note the coarse Maurer's clefts. In preparations stained first with Nile blue sulfate (in a moist chamber without prior fixation) and then with azure-eosin (Sarkisyan), coarse granularity of the Maurer's clefts type is revealed in erythrocytes containing young schizonts of mal. tertianae, whereas in erythrocytes with more mature forms of the parasites, Schüffner's dots appear sharply. Schüffner's dots are characteristic of Plasmodium vivax and are of great importance in differential diagnosis. Isolated reports on the finding of Schüffner's dots in malaria quartana and tropica have no practical significance.

E. Freyfeld.