Pityriasis lichenoides in children: clinicopathologic review of 22 patients.

Pityriasis lichenoides (PL) is a cutaneous disease of unknown origin, with an autoinvolutive course, that can occur in pediatric patients. Traditionally, acute and chronic variants have been described, but other special forms of presentation have been reported. We reviewed the clinical records and histopathologic specimens of all pediatric patients diagnosed with PL in our hospital from 1980 to 1995 to assess the clinicopathologic features of this disorder in our environment. Twenty-two of the 118 cases reviewed were pediatric patients less than 15 years old (12 males and 10 females, 18.6% of all patients). Their ages ranged from 3 to 15 years, with a mean of 9.3 years. Most of the patients (72%) had the chronic variant of the disease, while the remainder had an acute course. One patient suffered from acute ulceronecrotic PL. Systemic treatments prescribed were erythromycin in eight patients, PUVA in five patients, and methotrexate in one patient. Three patients had a prolonged course with more than two episodes. Acute and chronic PL are polar extremes, but individual cases cannot be classified only on the basis of histopathologic data, since coexistence of lesions in different stages of evolution can lead to sampling bias. Acute ulceronecrotic forms and the presence of a variable degree of cellular atypia in the infiltrate are liable to cause differential diagnostic problems with lymphomatoid papulosis (LP), which cannot be completely resolved on the basis of T-cell receptor clonal rearrangement detection.