Impetigo often presents as a shallow red erosion covered with a crust. The presence of suppuration, crusting and itching allows us to morphologically locate the non-bullous form of the disease within the group of eczematous diseases. Impetigo is identified by its location around the nose and mouth, its rapid onset and spread, the presence of pus beneath the crust, and its prompt response to antibacterial therapy. Other clues to the correct diagnosis include a history of infection, a paucity of inflammation compared to the extent of crusting, and recovery of streptococcal or staphylococcal bacteria. Oil culture.
The term infectious eczematoid dermatitis was originally used for those eczematous lesions that appeared on the skin around infected and weeping lesions. However, it is now clear that this eczema is due more to the macerating and irritating effect of the draining fluid than to the bacteria it may contain. Therefore, the rash around an ileostomy (draining sterile fluid) has a similar appearance to that of a colostomy (draining fluid with a high bacterial count). Therefore, this process can be seen as a variant of weakly irritant contact dermatitis; the term “infectious eczematoid dermatitis” is best left as a historical footnote in the annals of dermatology.
Perioral dermatitis patches and plaques are often covered with a small amount of yellow scale. As in seborrheic dermatitis, a disease to which it is related, the yellow is due to the exudation of small amounts of serum on the surface of the skin. Minute pustules may stud the surface of erythematous patches or plaques and are therefore also considered the condition. As the term “perioral” implies, this condition occurs in the lower half of the face. A characteristic feature is the presence of a narrow margin of normal skin that occurs between the lips and the beginning of the rash.
There are several types of sunlight-induced eczematous diseases. First, photosensitivity can be induced by internally administered drugs, such as tetracyclines, phenothiazines, thiazide diuretics, sulfonamide antibiotics, and nalidixic acid. Second, photocontact dermatitis may occur in a small percentage of patients who apply cosmetics containing musk ambrette, sunscreens containing para-raminobenzoic acid (PABA), PABA esters, cinnamates, or benzophenones; and at least in the past, soaps containing halogenated bacteriostatic agents. Third, chronic sun exposure that occurs over years can result in the development of hundreds of small, closely spaced, slightly crusted actinic keratoses superimposed on an inflammatory background. This process can be considered conceptually as a form of actinic dermatitis. Finally, the photosensitivity rash of systemic lupus erythematosus (the “butterfly rash”) is sometimes so intense that it takes on an eczematous morphology in a sun-exposure distribution pattern.