2025 – PAGE 149 – DERMATOLOGY

ERYTHEMA MULTIFORME (EM)

Erythema multiforme (EM) is an acute, immune-mediated condition with target lesions +/- mucosal involvement. It was previously thought to be on the spectrum of SJS/TEN, but that is no longer the case. Distinguishing erythema multiforme minor from erythema multiforme major is not straightforward, so that terminology is not likely to be tested. IF you are tested on the terminology, pick minor if the patient is not toxic. Both minor and major have tiny target lesions (probably dusky in the middle). Sometimes you have to use your imagination to envision the target. Lesions may just look a little darker on the inside of the lesion than the outside. Lesions usually start on the hand and/or feet and THEN progress to the trunk. There will be 0–1 mucous membranes involved (if more, then it may be a case of SJS or TEN). Possible etiologies include HSV, Mycoplasma, and Syphilis.

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(DOUBLE TAKE) NEONATAL LUPUS

The baby does NOT have lupus. Neonatal lupus occurs in children of mothers with SLE due to fetal exposure to maternal SLE-related antibodies. It is rare. Findings may include increased LFTs, petechiae, rash, scaling, thrombocytopenia, third degree AV heart block with bradycardia, or hydrops fetalis (fluid accumulation in two or more fetal compartments usually due to heart failure). Diagnose by sending maternal Anti-Ro or anti-La antibodies (AKA anti-SS-A or SS-B).

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RASHES WITH CENTRAL CLEARING (PEARL)

Hives/urticaria, Rheumatic Fever (“jonEs” = E. Marginatum = MARGINs progress to give central clearing), Tinea (raised border/ringworm)

RASHES WITH CENTRAL DARKENING/TARGET LESIONS (PEARL)

SJS/TEN (“target shooting, bull”), Brown recluse spider bite (see Emergency Medicine), Lyme Disease/Borrelia/Erythema Migrans

URTICARIA/HIVES

Urticaria (hives) is a pruritic rash due to an allergic exposure. Pink center with a more erythematous border. Giving histamine blockers (both H1 & H2) may be helpful.

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SCLERODERMA

Scleroderma patients have thickened skin with an ivory or waxy, appearance. Affects girls more frequently. The limited form is more common than the systemic form in children (located at one site only). Lesions may initially be painful and tender. Skin is often hard and may have a linear appearance. Treat with topical lubricants for limited cases. May have to use steroids or other immunosuppressives in more severe cases.

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