The Nature of Dandruff

cine: interest in a problem is inversely proportional to the square of its prevalence. Rare disorders evoke great interest; great minds and monies are applied to their study. Conversely, familiar things are scorned and neglected. Dandruff also illustrates an adverse effect of therapeutic advances: curiosity collapses when a means of control is developed. The power to subdue a disorder weakens interest in its inner qualities. Two paths of investigation, which have long occupied our attention, namely, CUTANEOUS MICROBIOLOGY and the HORNY LAYER, finally led us to the SCALP. We have been serious students of dandruff for almost a decade. It is our intent in this paper to tell what we have learned and to present an overview of dandruff in the light of our personal experience. We shall be less concerned here with raw data than with ideas of what dandruff is and how it behaves. I. DEFINITION Dandruff is excessive clinically noninflammatory scaling of the scalp. In the great majority of cases, diagnosis can be made almost instantly by simply inspecting and scratching the surface. Lesions elsewhere on the body call attention to disorders which also happen to involve the scalp, notably seborrheic dermatitis and psoriasis. Difilculties arise when the latter are chiefly confined to the scalp for inflammatory changes are masked in this location. Scalp skin is thick and redness and exudation may be hidden by layers of scale. Scaling itself is a very nonspecific sign. Great experience is needed to recognize the special morphologic qualities of different dermatoses, viz., the silvery scale of psoriasis or the greasy scale of seborrheic dermatitis. We always inquire about past and present skin disease. Wrong diagnoses, while not common, are frequent enough to cause some mischief. It is disquieting how often we have mistaken another process for dandruff, most often seborrheic dermatitis in older subjects. Diagnostic er