Master the board step 3

Master the Boards: USMLE Step 3
Diagnostic Testing
A definitive diagnosis can be determined with patch testing.
Treatment
Treatment is by properly identifying the causative agent and with antihistamines
and topical steroids.
Pityriasis Rosea
This is a pruritic eruption that begins with a “herald patch” 70–80 percent
of the time. It is erythematous and salmon colored and looks like secondary
syphilis, except that it spares the palms and soles, has a herald patch, and
the VDRL/RPR is negative. The lesions on the back appear in a pattern like a
Christmas tree (if the observer is especially imaginative).
It is mild and self-limited and usually resolves in 8 weeks without scarring.
Lesions that are very itchy may be treated with topical steroids.
Acne
Pustules and cysts occur and rupture, releasing free fatty acids that cause
further irritation. The contributing organism is Propionibacterium acnes. The
discharge, although purulent, is odorless.
Treatment
Mild disease is treated with the following:
··
Topical antibiotics, such as clindamycin, erythromycin, or sulfacetamide.
In addition, the bacteriostatic agent benzoyl peroxide is used.
··
Topical retinoids are used if these attempts to control the load of bacteria
locally are ineffective.
Moderate disease is treated with the following:
··
Benzoyl peroxide, combined with the retinoids tazarotene, tretinoin, and
adapalene.
Severe cystic acne is treated with the following:
· · Oral antibiotics, such as minocycline, tetracycline, clindamycin, and
isotretinoin: Oral retinoic acid derivatives are strong teratogens. Check
urine pregnancy test and make sure patients are on oral contraceptives if
they are females of childbearing age.
308