Histiocytosis with mixed cell populations.

Langerhans cell histiocytosis (LCH) and juvenile xanthogranuloma (JXG) are thought to originate from a common stem cell precursor, with divergent differentiation under different microenvironmental conditions. We describe an exceptional case of multiple cutaneous lesions in a 10-year-old boy, in which the coexistence of both LCH and JXG cell populations is found in every single lesion. The presence of Birbeck granules and CD207 (langerin) immunostaining in the LCH component would argue against the diagnosis of indeterminate cell histiocytosis (ICH).

Parvovirus B19-Associated Microvesicular Eruption.

We report on a 3-year-old girl with a microvesicular generalized rash in whom primary infection by parvovirus B19 was demonstrated by seroconversion. To our knowledge, this is the first instance of an eruption arising from parvovirus B19 with this peculiar clinical pattern.