What common skin diseases resemble some phases of eczema?
Psoriasis, seborrhœa, sycosis, scabies and ringworm.
How would you exclude psoriasis in a suspected case of eczema (squamous eczema)?
Psoriasis occurs in variously-sized, rounded, sharply-defined patches, usually scattered irregularly over the general surface, with special predilection for the elbows and knees. They are covered more or less abundantly with whitish, silvery or mother-of-pearl colored imbricated scales. The patches are always dry, and itching is, as a rule, slight, or may be entirely absent. Eczema, on the contrary, is often localized, appearing as one or more large, irregularly diffused patches; it merges imperceptibly into the sound skin, and there is often a history of characteristic serous or gummy oozing; the scaling is usually slight and itching almost invariably a prominent symptom.
How would you exclude seborrhœa (eczema seborrhoicum) in a suspected case of eczema?
Seborrhœa of the scalp is more commonly over the whole of that region and is relatively free from inflammatory symptoms; the scales are of a greasy character and the itching is usually slight or nil. On the other hand, in eczema of this region the parts are rarely invaded in their entirety; there may be at times the characteristic serous or gummy oozing; inflammatory symptoms are usually well-marked, the scales are dry and the itching is, as a rule, a prominent symptom. These same differences serve to differentiate the diseases in other regions.
How does scabies differ from eczema?
Scabies differs from eczema in its peculiar distribution, the presence of the burrows, the absence of any tendency to patch formation, and usually by a clear history of contagion.
How would you exclude ringworm in a suspected case of eczema?
Ringworm is to be distinguished by its circular form, its fading in the centre, and in doubtful cases by microscopic examination of the scrapings.