CHICAGO – Pityriasis lichenoides chronica (PLC) is a benign, chronic disorder that can last from 1 to 5 years, yet no formal treatment standards exist.

“Topical corticosteroids will not alter the course of the disease, but they provide symptomatic relief when there is pruritus,” Sibel Ersoy-Evans, MD, said at the World Congress of Pediatric Dermatology. “Oral antibiotics, especially erythromycin, and phototherapy are the most common modalities used in children. Systemic immunosuppressants are rarely needed.”

Dr. Ersoy-Evans, a dermatologist at Hacettepe University in Ankara, Turkey, described pityriasis lichenoides (PL) as a spectrum with two polar ends: PLC and pityriasis lichenoides et varioliformis acuta (PLEVA). Its incidence and prevalence are unknown, but age distribution peaks at 2, 5, and 10 years of age. The average age of onset is 6.5 years, it’s slightly more common in boys, and there is no racial or ethnic predilection.

The specific cause of PL is unknown, yet one of the three main theories holds that it’s an inflammatory condition triggered by infections or drugs. “In 30% of cases, there is a recent history of infection,” Dr. Ersoy-Evans said. “Acute eruptive presentation, early onset, as well as the presence of CD30-positive and CD8-positive lymphocytes support this theory.” A second theory holds that PL is associated with T-cell dyscrasia. “There are reports about T-cell receptor clonality in PL lesions and its similarity and association with lymphomatoid papulosis and mycosis fungoides, and the presence of CD30-positive and CD7 deletions,” she said. “There are also reports about PL progressing to lymphoma.” The third theory is that PL is an immune complex mediated hypersensitivity vasculitis based on reports of immunocomplex imposition in PL lesions.

PLEVA presents with symmetrical, reddish-brown papules that later evolve into vesicular, purpuric, necrotic papules. The scalp, face, mucosa, palms, and soles are spared. Resolution occurs with varioliform scarring and dyspigmentation in 2-18 months. On the other hand, chronic PL is characterized by asymptomatic scaly papules and plaques. The lesions start de novo or evolve from PLEVA lesions and they resolve with hypo-hyperpigmentation in about 8-20 months. In what is believed to be the largest study of its kind, Dr. Ersoy-Evans and her associates respectively reviewed 124 patients with PL. They observed that 57% of patients had PLEVA, primarily those who were white, and 37% had PLC (J Am Acad Dermatol. 2007;56[2]:205-10). The median age of onset was 6 years in PLC patients, versus 5 years in those with PLEVA. Age peaks were observed at 2-3 years and 5-7 years.

They also observed that 30% of cases had a history of recent infection prior to the eruption. “Most patients had generalized distribution, and there wasn’t a significant difference in duration according to the distribution of the lesions,” she said. “Postinflammatory pigmentary changes were observed in 90% of the cases, most commonly hypopigmentation. Pruritus was the most common symptom observed, and the disease was relapsing/recurring in 77% of patients. The duration was longer in PL patients.”

A separate study of 25 children and 32 adults with PL found that hypopigmentation was more common in children (72% vs. 19%, respectively), fewer children experienced remission (20% vs. 78%), and phototherapy was more effective than oral antibiotics in children (Br J Dermatol. 2007;157[5]:941-5).

PL runs a chronic, remitting course in 25%-77% of patients, but there are infrequent reports about progression into cutaneous T-cell lymphoma. “We have not observed any lymphoma development in our cohort with a 10-year follow-up, but long-term follow-up is necessary, especially if clonality is present,” Dr. Ersoy-Evans said. The diagnosis of PL is mostly clinical, but histologic examination may be necessary in some cases. “CD8-positive cells predominate in PLEVA, whereas CD4-positive cells predominate in PLC,” she said.

In the review of 124 patients that she and her associates published in 2007, erythromycin estolate or ethylsuccinate was administered to 80% of children, and 67% of these children showed at least a partial response, with a median response time of 2 months.

In a separate study of 24 children with PL, the response rate was highest (83%) after 3.8 months of erythromycin therapy (Ped Dermatol. 2012; 29[6]:719-24). Dr. Ersoy-Evans stated that oral erythromycin should be continued at least 2 months for a response.

A separate study evaluated the use of phototherapy in 18 children with PLC for a mean of 3.7 months (Ped Dermatol 2008;25[6]:599-605). Among 12 patients who received broadband ultraviolet B radiation for a mean of 3.7 months, the response rate was 83%, which was achieved after a mean of 18 sessions. All five patients who received narrow-band UVB cleared, and the mean number of sessions for a response was 22. One patient who received psoralen and ultraviolet A therapy had no response. A larger review of the published literature found that the delivery of narrow-band UVB has the lowest recurrence rate in PL patients treated with phototherapy (Am J Clin Dermatol. 2016;17:583-91). “Given the efficacy and favorable side effects, I think that phototherapy can be a promising option for PL in children,” Dr. Ersoy-Evans said.

She reported having no financial disclosures

dbrunk@frontlinemedcom.com

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