Pediatric emergency medicine trisk 342

palmoplantar keratoderma. There are often characteristic islands of sparing (
Fig. 70.8 ). It is most often confused with psoriasis, which it can closely
resemble, but PRP lesions lack the overlying silvery scale of psoriasis.
PRP is often idiopathic and sporadic in its occurrence. PRP can occur as a
postinfectious process (most commonly streptococcal and occasionally
HIV), as an adverse drug reaction, and in adults, as a paraneoplastic
phenomenon associated with a variety of malignancies. The condition has
also been associated with CARD mutations and autosomal dominant
inheritance (early-onset form).
Long-term treatments include use of emollients, topical corticosteroids,
topical retinoids, vitamin D analogs, topical calcineurin inhibitors, and
systemic agents such as phototherapy and biologic agents (infliximab,
ustekinumab, etanercept, adalimumab).


FIGURE 70.8 Pityriasis rubra pilaris. Note the orange or salmon-colored appearance of
the papules.

In the emergency department, identification of an affected child should
include evaluation for possible infectious triggers and treatment for any


active infections. Referral to a dermatologist is recommended to institute
longer-term treatment as needed.

Pityriasis lichenoides
Pityriasis lichenoides is a lymphocytic inflammatory skin condition that
classically has been divided into the acute (pityriasis lichenoides et
varioliformis acuta or PLEVA) form and the chronic (pityriasis lichenoides
chronica or PLC) form. This distinction may be artificial as there are often
overlapping features of both in an individual patient so the term pityriasis

lichenoides (PL) is generally preferred. There is a rare and severe form
known as febrile ulceronecrotic Mucha–Habermann (FUMH) syndrome.
Patients present with persistent crops of skin lesions that vary in
appearance from crusted vesicles and papules ( Fig. 70.9 ) to scaly patches
and small plaques that may be hypopigmented in some cases ( Fig. 70.10 ).
These lesions are most often asymptomatic. There is often a predilection for
sun-protected areas, and in summertime, areas exposed to sunlight often
show fewer skin lesions. In FUMH syndrome, these lesions are often
accompanied by fever and larger, often painful, ulcerated papules and
plaques.
At times, the condition may be initially misdiagnosed as varicella, but PL
patients are generally afebrile (except in FUMH), and the lesions of PL
persist for months to years. At other times, the condition may resemble PR
but PL will persist for months to years, differentiating it from PR. Infants
who develop crusted papular eruptions that resemble PL should also be
evaluated for the possibility of LCH.


FIGURE 70.9 Crusted papules of pityriasis lichenoides et varioliformis acuta.