PATHOGENESIS OF ALOPECIA By NORMAN ORENTREICH, M.D.* Presented May 12, 1960, New York City PRESCRIPTIONS FOR THE TREATMENT of disorders of the hair, such as hair loss in men, hair loss in women, dermatitis of the scalp and graying, date back over 5000 years to the Egyptian papyri which were the pharma- copeas of their day. The biblical classification of hair loss was simple--contagious or non- contagious. The following is our attempt at an etiologic classification of hair loss: ETIOLOGIC CLASSIFICATION A. Congenital and Inherited B. Neoplastic (a) Benign (b) Malignant C. Acquired (a) Traumatic (1) Physical (2) Chemical (3) Ionizing Radiation (b) Hormonal (c) Infectious (1) Localized (2) Systemic (d) Neurologic and Psychiatric (e) Poisons, Drugs and Occupation (f) Nutritional and Metabolic (g) Dermatologic Disorders Hair loss can involve the living hair follicle or the keratinized hair shaft. When the hair shaft alone is involved hair loss is temporary since the follicle continues to produce hair. Involvement of the living follicle may result in stoppage of hair growth and the falling out of hair. This may be followed by the immediate regrowth of a new hair, the temporary failure to regrow a hair or the persistent inability to regrow a hair from an existing follicle. If the follicle is destroyed loss of hair is permanent. * Assistant Clinical Professor Dermatology and Syphilology, New York University Post- Graduate Medical School (Dr. Marion B. Sulzberger, Chairman), New York, N.Y. 479

480 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS A. CONGENITAL AND INHERITED Congenital alopecia occurs as complete absence of hair or patches of alopecia existing from birth and may be associated with other congenital ectodermal defects such as defective teeth, nails and other adnexae (Figs. 1, 2 and 3). Rarely does normal hair develop. In monilethrix there are beaded hairs which break easily close to the scalp. The hair is dry and fragile with a shimmering reflection to incident light. Occasionally this disorder improves spontaneously, especially after puberty. Trichokinesis or pili torti refers to the twisting of hairs on their long axes. The shafts fracture easily. This condition closely resembles and may coexist with monilethrix. Ichthyosis or "fish skin" disease may occur as simple dryness or be so severe as to produce the "harlequin fetus" and the "collodion baby." dndro-genetic alopecia is produced by androgens, but only in persons genetically predisposed. Male-pattern alopecia is the outstanding example of this type. I believe that hair loss in the female may be caused by endo- genous or exogenous androgens triggering the genetic predisposition. Physiologic alopecia of the newborn is the spontaneous and temporary hair loss which first appears in the early weeks of neonatal life. B. NEOPLASTIC Benign (Figs. 4 and 5) and malignant (Fig. 6) neoplasms can produce hair loss by pressure,displacement, replacement or systemic influences. Figure 1.--Congenital Alopecia in 30-year-old female.