[Psoas abscess as a chicken pox complication].

Chicken pox is the most frequent exantematic illness; usually its course is self-limited and benign. Several bacterial complications are described due to the disruption of the skin as a defensive barrier because of the characteristics of the injuries and the associated inmunodepression. Psoas abscess is a rare illness and it's difficult to diagnose, with a general unspecified clinical presentation. We present the case of a 5-year-old girl, on her fifth day of chicken pox, who consults about a febrile convulsion, from which she recovers without any neurological symptoms, referring to functional impotence of her inferior left limb and pain in the lumbar and gluteal zone, which irradiates to the homolateral hip, making deambulation impossible. The definitive diagnosis was made with a CAT at hospital admission. The germ isolated was community-acquired methricillin-resistant Staphilococcus aureus. Treatment consisted in surgical drainage and endovenous antibiotics.