Musculoskeletal pain in children are common, affecting about 10-20 % of school children.1,2 Various local and systemic, acute and chronic, benign and malignant conditions are associated with musculoskeletal pain.3 Arthritis in childhood is common. The pattern, presentation and duration of arthritis help differentiate between the various possible diagnoses.4 There are some common causes of articular involvement in children.5 Arthritis is manifested as a swollen joint or a joint having at least 2 of the following conditions: limited range of motion, pain on movement, or warmth overlying the joint.6 Children with arthritis more commonly present with complaints of joint swelling and/or gait disturbance.7 It is important to remember that all the limb and joint pains are not arthritis and all arthritis are not painful.3
The most important aspects of the diagnosis are comprehensive history taking and a detailed clinical examination.8 Clinical information in patient including demography, disease chronology, inflammatory nature, progression, distribution of joint involvement and extra-articular manifestations help narrow the diagnostic possibilities. A carefully conducted history and physical examination are the initial and most important steps in narrowing the differential diagnosis and guiding the diagnostic evaluation. Important aspects to be emphasized from the history taking are as follows: age of onset of the disease, gender, onset of disease and duration and characteristics of the pain and/or stiffness.3 There are some red flags signs (raise concern about inflammation, infection, malignancy or non-accidental injury) for potentially serious conditions. Red flags signs are followings fever, malaise, systemic upset (reduced appetite, ?weight loss, sweating), bone or joint pain with fever , refractory or unremitting pain, persistent night-waking, incongruence between history and presentation.9 
The focused examination of the affected joint should include inspection of the skin for warmth, redness, swelling, and soft tissue involvement, using the contralateral side for comparison. Passive and active range of motion should be observed.10 A recently developed and validated tool is the pediatric Gait, Arms, Legs, Spine screening (pGALS), which is a simple musculoskeletal screening examination that can be performed in a few minutes (Figure 1).11 The pediatric Gait, Arms, Legs, Spine screening (pGALS) has been demonstrated excellent sensitivity to detect abnormality, quick to perform with highly acceptable to school age children and their parents.9
Laboratory tests in rheumatology are important tools that help to support the diagnosis of autoimmune diseases, evaluate the disease activity, monitor the side effects of therapy, and also assist the physician to exclude rheumatologic mimics.12 Laboratory investigations are an integral part of evaluation of a child with rheumatic disease. In rheumatic diseases markers of inflammation like CRP and erythrocyte sedimentation are usually raised. In addition, various autoantibodies like anti- nuclear antibody, rheumatoid factor, anti-neutrophil cytoplasmic antibody help in diagnosis of systemic autoimmune rheumatic diseases. 13