The mode of growth of eccrine duct milia.

Light and electron microscopic studies were performed utilizing serial sections in 10 patients with secondary milia to clarify the incidence of eccrine duct milia and to demonstrate the life history of the milia. Out of 69 milia after blistering taken from 8 patients, 52 were found to connect with the eccrine sweat duct (75.4%) while only 1 connected with the hair follicle (1.5%). In the control group, of 4 milia taken from 2 patients, 2 were found to connect with the eccrine sweat duct and 1 with the hair follicle. Various degrees of milium formation were observed ranging from incomplete and having either concave-shape, U-shape, capped U-shape, or O-shape. The eccrine duct milia in all types possess structures resembling the epidermal sweat duct unit. The epithelial cells constituting the recess or cyst differ from epidermal cells.