Scales

Scales are collections of cells of the stratum corneum, which, instead of pursuing their usual and normal course, collect in undue number and quantity, and are loosely or firmly  attached to  the skin in more  or less  heaped-up

masses. When these scales are small in size, loosely at­tached, like a fine powder or meal scattered over the sur­face, they are termed farinaceous; on the other hand, when large, thick, heaped up, and firmly attached, they are called furfuraceous.

The principal diseases in which  scales are found,  and their chief features are:

1. Dermatitis   exfoliativa;   Large   scales, consisting of flakes  of homy  epidermis;   sometimes  several  inches in extent.
2. Eczema;   Medium  size,  scales  occurring in the last stage of the disease, and frequently preceded by exudation and crusting.
3. Ichthyosis; Very adherent thick scales, the disease commencing in early life and continuing indefinitely.
4. Lupus   erythematosus;   Very   fine   adhering   scales, situated on a reddened, infiltrated base.
5. Pemphigus foliaceus; Large scales, due to imperfect formation of bullae.
6. Pityriasis simplex; Fine white scales on a surface but little affected otherwise, and readily exfoliating.
7. Pityriasis rubra; Fine scales on a reddened surface, usually generalized.
8. Psoriasis; Thick, adherent, imbricated white scales on a reddened infiltrated surface, more or less generalized.
9. Syphilis;  Small scales at the summit of papules, or thicker and larger on reddened infiltrated surface more or less generalized.
10. Trichophytosis capitis; Fine scales among hairstumps on round patches.