RESUMEN
A child with polyarthritis is always a diagnostic challenge for the treating physician. By definition, polyarthritis, taken in context as a subgroup of juvenile idiopathic arthritis, is defined as inflammation of more than 4 joints on physical examination. Though the exact incidence and prevalence of polyarthritis in childhood is not known, it is not uncommon in pediatric practice. Polyarthritis can be a clinical manifestation of diverse disease processes and the differential diagnosis is understandably very broad. It can be caused directly by an infectious agent or indirectly by immune mechanisms, may be a component of a systemic disease process or may be idiopathic. The presentation can be acute or chronic. It can represent a benign self limiting illness requiring no specific treatment or may be a severely disabling condition with significant morbidity and, in some cases, even mortality.While in some situations it may be possible to arrive at a provisional clinical diagnosis right at the outset, in others the diagnosis gradually evolves over a period of time. As in most other arthritides, the most important aspects of the diagnosis are a thorough history and a detailed clinical examination. Relevant laboratory investigations can help in facilitating the diagnosis but can often also mislead the treating physician. Hereby we present a clinical approach to a child with polyarthritis.