Abstract
The sinuses of the axillary nodes were studied in 59 breast cancer patients. Three types of reaction were defined in them: sinus histiocytosis, a mixed sinus reaction and sinus catarrh. Sinus histiocytosis, as defined here, was virtually confined to the node-negative cases; sinus catarrh was common to both node-negative and positive cases, but increased with tumor size in the former. Transition may occur from sinus histiocytosis, via the mixed reaction, to sinus catarrh, and the establishment of the later may facilitate tumor spread.