ECZEMA. A BOILING OUT. A PUSTULE.
General method of eruption. Successive advancing lesions. Definition. Causes: usual factors and special susceptibility.
This term, standing for what boils out, has long been applied to vesicular eruptions on the skin, but inasmuch as the inflammation rarely stops short with vesiculation, but usually in part at least goes on to more advanced lesions, it must be held to include in many cases erythema, papules, vesicles, pustules, crusts, desquamations and erosions. All of these may coexist or succeed each other in the same subject, so that considerable latitude must be allowed to the name to cover all parts and stages of the same attack. Dermatologists have defined eczema as a non-infectious inflammation of the skin with multiform manifestations, but recent observations would indicate that it may at times, at least, be contagious, and micrococci have been found in the serum of the vesicles, while the very occurrence of pus must virtually imply the existence of a bacterial infection. Doubtless different diseases pass under this name in the different genera and species, and even in the same variety of animals, yet until we learn to discriminate sharply the one from the other, it is convenient to consider the whole as a kindred clinical group, if not a pathological entity.
Definition. An acute or more frequently, a chronic inflammation of the skin and sometimes of the mucosæ, characterized by itching, erythema, papules, vesicles, serous or sero-purulent exudation with squama or crusts and loss of hair, and usually largely due to an internal cause. The exudative condition has suggested a catarrh of the skin.
Causes. These are the usual causes of skin disease, local and general, together with a special susceptibility, under which, what are ordinary irritants produce this characteristic disease. Many local irritants can produce eczema, but again it is often the case that these factors will operate on a given susceptible subject while on another they are without much effect. This susceptibility is called a “dartrous diathesis” by the French writers, while most English and American writers are willing rather to find the hidden cause or causes in the disorder of internal organs (digestive, hepatic, urinary, generative, hæmatic, trophic, infective, plethoric, atonic).