Drug eruptions (dermatitis medicamentosa). Diagnosing drug eruptions has become a common experience to practitioners in all branches of modern medicine. The profusion of drugs now available, the continuous influx of new drugs, and the capability of drugs to cause actions different from or in addition to their pharmacologically desirable actions make adverse cutaneous reactions an inevitable fact of modern medical practice. The kinds of cutaneous reactions are varied. Exanthems (erythematous, morbilliform or maculopapular), urticaria, fixed drug eruptions, and erythema multiforme are the most common. Figure 18-1 is an urticarial reaction from Augmentin and Fig. 18-2 shows a morbilliform eruption from ampicillin. Constitutional symptoms of low-grade fever and malaise may be associated with such drug eruptions. Morbilliform eruptions from ampicillin are more frequently seen in children with infectious mononucleosis.
Drug eruptions (dermatitis medicamentosa). Drug eruptions may mimic nearly the entire range of dermatoses of other causes. One of the commonest forms is the exanthematic, whose lesions are usually erythematous and edematous. Common causes of drug eruptions include ampicillin, cephalosporins, semisynthetic penicillins, and barbiturates. We have just illustrated cases that were morbilliform. Illustrated here are cases clinically resembling erythema multiforme.
Congenital nevomelanocytic nevus; “split” of the eyelid. A sharply demarcated, brown plaque, involving the upper and lower eyelids in a 45-year-old Asian female. Nevomelanocytes migrate from the neural crest to the skin after the 10th week in utero but before 24 weeks when splitting of eyelids occurs.
Bee, wasp, yellow jacket, hornet or fire ant stings most often trigger allergic reactions. However, most people are not allergic to insect stings and may mistake a normal sting reaction for an allergic reaction.
Cavernous hemangiomas (also called angioma cavernosum or cavernoma) are similar to strawberry hemangiomas but are more deeply situated. They may appear as a red-blue spongy mass of tissue filled with blood.