Periductal inflammation and cigarette smoke.

Background: Cigarette smoking has been implicated in the etiology of periductal mastitis. The mechanism by which it causes inflammation around the mammary ducts is unknown.

Study Design: Inflammation and dilatation of the mammary ducts were compared in two groups of women with proven histologic diagnoses of periductal mastitis (PDM, n = 133) and intraductal papilloma (IDP, n = 98) over an eight year period. This study was done to determine if the number of cigarettes smoked correlated with the amount of periductal inflammation seen in PDM. Duct dilatation, periductal inflammation, and squamous metaplasia were assessed objectively by two pathologists without knowledge of the clinical parameters.

Results: Women with PDM were significantly more likely to be smokers than women with IDP (p < 0.001). Women with severe periductal inflammation were more likely to be younger (p < 0.05) whereas those with duct dilatation were more likely to be older (p < 0.02). Women with PDM who were heavy smokers (more than ten cigarettes per day) had more periductal inflammation (p = 0.0006) and squamous metaplasia of the lactiferous ducts (p < 0.02) compared with light or nonsmokers. Duct dilatation did not correlate with smoking habits.

Conclusions: Cigarette smoking appears to be an important etiologic factor in periductal mastitis and appears to have direct toxic effects on the mammary ducts.