[Lymphomatoid papulosis in children: report of 9 cases and review of the literature].

BACKGROUND Lymphomatoid papulosis is a rare lymphoproliferative T cell CD30+ disease with excellent prognosis which affects almost exclusively adult patients, being rarely in the childhood; thus the clinic and pathologic spectrum and the risk of evolution to another type of lymphoma are not well defined in the pediatric group. OBJECTIVE The aim of this article is to analyze the characteristics of infantile lymphomatoid papulosis and review the literature. MATERIAL AND METHOD A retrospective study analyzing the characteristics of 9 patients aged up to 18 diagnosed of lymphomatoid papulosis attended in our department from 1995 to 2009 was performed. RESULTS The study included 7 boys and 2 girls aged between 2 and 17. Pityriasis lichenoides acuta's lesions appeared associated before and after lymphomatoid papulosis' development in 2 and 1 cases respectively. The lesions resolved spontaneously, leaving a postinflammatory hyperpigmentation (77%) or hypopigmentation (23%). The development of varioliform scars occurred in over 77% of cases. Histologically, all cases showed features compatible with type A of lymphomatoid papulosis. Molecular studies showed monoclonality in the 3 cases in which this technique was done. CONCLUSIONS Infantile lymphomatoid papulosis is a rare entity clinically manifested as the adult form. This lymphoproliferative disease, which is occasionally associated with pityriasis lichenoides acuta, shows features compatible with the type A or histiocytoid pattern in the histological analysis. The development of other lymphoproliferative disorders is less frequent in the infantile form than in the adulthood. The prevalent association among pityriasis lichenoides and lymphomatoid papulosis observed in our analysis, as well as the difficulties which supposed to differentiate between these two pathologies in various cases, suggest that those entities could be part of a common clinical and pathological spectrum.