MILIA

MILIA (Latin: panicum), white comedones (synonyms: acne albidans, grutum), firm nodules ranging from pinhead to pea size, white and yellowish-white, pearl-colored, which are essentially keratin cysts; located mostly in groups and almost never coalescing, milia are predominantly localized on the facial skin, mainly on the eyelids, in the infraorbital and zygomatic areas, on the forehead and on the temples; occasionally they are found on the genital organs and trunk. After a superficial incision of the keratin covering, a white, dense core, consisting mainly of keratin, can be easily extracted from each element of M. Primary spontaneously occurring M. and so-called secondary M.- pseudomilium of Balzer are distinguished; the latter often form on scars (for example, on burn scars) as well as in various bullous eruptions: in pemphigus, herpesiform dermatitis of Dühring, etc.; the development of secondary M. is particularly characteristic in the dystrophic form of congenital epidermolysis bullosa (see Epidermolysis bullosa hereditaria). Histologically, M. consist of layered, onion-shaped keratin masses surrounded by a cystic wall lined with epithelial cells; in this keratin mass, a dense central core and a loose peripheral zone can almost always be distinguished. Fat is sometimes mixed to varying degrees with the keratin; Unna considers M. as a pearl keratoma without admixture of fat and fat cells. Milium most often forms in the deep parts of hair follicles (vellus hairs), and it is almost always possible to detect a connection between the wall of M. and the follicles even in cases where M. develop in what appears to be a constricted epithelial cord from the follicle; much less frequently, the excretory duct of a sweat gland is found in the wall of M.; the question of whether such cysts arise due to expansion of these ducts or due to impaired function has not yet been resolved. Keratin cysts without connection to follicles are more often observed on the scrotum. Clinically, it is impossible to distinguish M.-follicular cyst from milium-like formations associated with the excretory ducts of sweat glands (Gans), as well as sebaceous glands. Cases of so-called miliaria sebacea of Jacquet are clinically distinguished by the presence of suppurating vesicles. According to Hinselmann, miliaria sebacea represents a lesion analogous to acne vulgaris. The etiology of M. is unknown; in most cases, M. apparently must be considered as formations of the type of nevus. According to Darier, primary milium is a "cystic birthmark," secondary - a retention tumor. In rare cases, M. is congenital (M. congenitale) and generalized; thus, in the case of Balzer and Galliot, in a 6-year-old child from 6 months of age, M. were scattered all over the body; in the case of Little, a 3-month-old child was covered with hundreds of milia. Jadassohn observed multiple M. as an occasional familial disease. Siemens saw M. several times in one of two identical twins; the second twin was always free of them. - Treatment consists in making an incision in each nodule with a scalpel and extracting its contents; to prevent recurrence, it is recommended afterward to destroy the remaining cystic wall by electrolysis or with a galvanocautery knife; some advise injecting a few drops of ether solution or zinc chloride solution. - Under the name Colloid-milium of Wagner (E. Wagner), synonyms: pseudomilium colloidale of Pellizzari, degenerescence colloide du derme of Besnier and Balzer, hyalom, colloïdome miliaire, a very rare, distinctive skin disease is known, having nothing in common with ordinary milium and characterized by the appearance on the skin of the cheeks, forehead, less frequently the neck and upper extremities, of small, pinhead-sized, yellowish, shiny, soft, painless tumors, from which a gelatinous content consisting of colloid is obtained on expression, which is why Balzer proposed to call this disease colloid degeneration of the skin (degenerescence colloide du derme); collagen and elastin of the upper parts of the true skin turn respectively into collacin and elacin, which is detected by microchemical reactions. In diagnosis, it is necessary to remember the possibility of confusion, mainly with hydrocystoma of Robinson and hydroadenoama of Jacquet and Darier. Etiology is unknown. - Treatment: removal of tumors with a sharp curette, galvanocautery, or with snow CO₂.