Lymphomatoid papulosis in children: a retrospective cohort study of 35 cases.

Background: Lymphomatoid papulosis (LyP) is a rare entity, considered to be part of the spectrum of the CD30(+) cutaneous lymphoproliferative disorders. About 10% to 20% of the adult LyP patients will develop an associated lymphoid malignancy. Only a few cases of LyP have been described in children, and the risk of associated lymphoid malignancies in these patients is not known.
Objectives: To study the association between childhood onset of LyP and other malignancies and to determine the clinical characteristics in this subgroup of patients.
Design: Retrospective cohort study.
Setting: Referral center at a university hospital. Retrospective registry for patients with LyP of childhood onset (< or =18 years). Patients Thirty-five patients with childhood-onset LyP (19 boys and 16 girls) were interviewed by telephone using a standardized questionnaire. The median duration of follow-up was 9.0 years. All included patients were confirmed by histologic examination.
Results: The age distribution was significantly different, with boys having an earlier onset of LyP (P =.03). Of the 35 LyP patients, 3 (9%) developed a malignant lymphoma; all were diagnosed as having non-Hodgkin lymphoma. Compared with the general population, patients with childhood-onset LyP have a significantly increased risk of developing non-Hodgkin lymphoma (relative risk, 226.2; 95% confidence interval, 73.4-697.0). More than two thirds of the patients reported being atopic, which is significantly more than the expected prevalence of atopy (relative risk, 3.1; 95% confidence interval, 2.2-4.3).
Conclusions: Lymphomatoid papulosis presents similarly in children and adults, including the risk of lymphoid malignancies. Therefore, all LyP patients should be closely monitored throughout their lives.