The biochemistry of breast cyst fluids and duct secretions.
Research Dept., Santa Barbara Breast Cancer Institute, CA 93108, USA.
The ratio of potassium to sodium concentrations in breast fluids has led other
investigators to the subclassification of cysts into two types: 1) apocrine
(secretory) cysts with high potassium and low sodium, and 2) attenuated
(flattened) cell cysts with low potassium and high sodium content. Apocrine cells
are thought by some to actively secrete potassium. Cell typing is considered
important as apocrine cysts are more likely to be bilateral, multiple, recurrent,
and serve as markers for epithelial cell atypia. A retrospective study of the
biochemical analyses of 58 cyst fluids and 28 duct secretions obtained by nipple
aspiration was conducted. Potassium and sodium concentrations obtained from 12
cyst fluids were statistically correlated with creatinine concentrations.
Evidence is presented indicating that micro cysts are initially apocrine in cell
type and are more likely in continuity with the terminal ductal-lobular unit. It
is postulated that apocrine cysts undergo cellular desquamation and lysis,
becoming attenuated cysts. The ratio of potassium to sodium is altered by cell
degradation rather than active secretory processes. Biochemical contents of cysts
and nipple aspiration fluids are compared.