(Acne albidia; Strophulus albidus; Grutum)
Definition. A small, yellow or pearly-white, non-inflammatory cystic formation, situated just under the epidermis, and usually located on the face.
Symptoms. The lesions are pin-point- to pin-head-sized, yellowish or whitish papules that appear to be just within or upon the skin but occasionally project above it and look as if filled with a milky fluid. They develop slowly and persist for a long time, very rarely becoming pea-sized or larger and finally, if not removed, disappear with the normal exfoliation of the epidermis. They present no subjective sensations and are of little clinical importance other than a cosmetic blemish. They may be found on the face, especially about the eyelids, cheeks and temples, on the external genitals of men and women and about scar tissue.
Etiology and Pathology. Milia may occur at any age but are most common in the adolescent and early adult periods. They may occur in infants (strophulus albidus) and are occasionally congenital. They have been found associated with comedones and acne, have been noted about the edges of scars and have followed erysipelas and pemphigus but no exact cause is known. The condition result from the retention of sebaceous matter in one or more acini of the sebaceous glands or possibly its seat is in the hair-follicles. Pathologically most milia consist of a fatty nucleus covered by several concentric layers of corneous epithelia. Calcareous, horny and colloidal degenerative changes have been found in these lesions.
Diagnosis. Milia should not be mistaken for any other condition. Vesicles of the same color are usually acute in development and have easily demonstrable liquid contents. Xanthoma simplex, which may be found about the eyelids, cannot be removed by the means employed to remove milia and are always of a pronounced yellowish hue. Comedones present a black point at the opening of the sebaceous duct and their shape on removal is quite unkike milia.
Prognosis and Treatment. The former is invariably good because the disease is benign, amenable to treatment and scarring does not follow its removal. In infants and young children the frequent use of soap and water, or the occasional use of a mild sulphur ointment (20 to 40 grains to the ounce) is all that is necessary. In adults the lesions may be gently incised with a milium or acne knife and the contents pressed or turned out with the same instrument. Immediate application of very hot water for a few moments will allay the slight inflammation and there should be no bleeding or scarring. Occasionally it may be wise to cauterize the sac with tincture of iodin or a 50 per cent. solution of chronic acid. In the case of milia of the male genitals, electrolysis is the most satisfactory method.