Group Identification of Eczematous Diseases-Skin Disorders

Both the papulosquamous diseases (group 9) and the eczematous diseases (group 10) are characterized by the presence of scaling red papules and plaques. Separation of these two groups is primarily based on the predilection of the eczematous lesions to demonstrate evidence of epithelial disruption. Secondary characteristics helpful in identifying eczematous disease include the presence of indistinct (nonsharp or diffuse) marginal ion and lichenification.Epithelial Disruption The features of epithelial disruption are listed and are briefly reviewed here. The most easily recognized evidence for epithelial disruption is the presence of linear or angular erosions (excoriations) secondary to scratching, but excoriations will not always be present. Thus careful examination for weeping, crust, yellow scale, and minute fissures is imperative. Weeping is identified by a sense of wetness on palpation. This wetness is due to the presence of serum on the surface of the skin and can only be found when the barrier layer of the epithelium has been broached. Crusting occurs when water from the serum on the surface of the skin evaporates, leaving behind solid serum proteins. The physical appearance of crusts is described . Yellow scale occurs when the amount of serum exuded is very slight. In this situation there is insufficient protein to form crusts, instead, the serum lightly coats the scale that is present. Small fissures are the most subtle sign of epithelial disruption and are all too often overlooked. These fissures are too narrow to be easily recognized as erosions and instead appear as thin red lines that wend their way in and around small islands or scale and/or normal-appearing skin. They represent tiny cracks in the outer portion of the epidermis; they are not deep enough or wide enough to allow for visible escape of serum. Nonsharp Margination. In the papulosquamous diseases the transition from normal to abnormal skin occurs so abruptly it is possible to place a pencil point exactly where the lesion stops and normal skin begins. In eczematous disease the zone of transition generally occurs over a space of 2 mm or more. In making this distinction between the two groups, however, the entire 360 circumference must be taken into consideration. This is necessary because in many eczematous diseases, some portion of anyone lesion may well be sharply marginated. The key feature is that nonsharp ("diffuse") margination will be present in some significant proportion of eczematous lesions, whereas the sharp margination will occur around the entire lesion in papulosquamous disease. Lichenification. Patients with eczematous disease recognize that scratching is detrimental and, therefore, often substitute rubbing for scratching. Chronically rubbed skin thickens in a way that increases the appearance of the normal crosshatch markings of the skin. In addition, lichen-type scale develops. The combination of these three features represents lichenification. Lichenification does not develop in all of the eczematous diseases, but it is not seen in conditions from any of the other nine groups. It is thus a feature with low sensitivity but high specificity. Separation of the eczematous diseases from the papulosquamous diseases can be one of the most difficult aspects of using the diagnostic algorithm. When such difficulty occurs, it is both expedient and desirable to form the list of differential diagnoses from diseases in both groups.