Marrow pain

• Leukemia
• Pain is nocturnal, occurs when move arms or walk
• And/or cannot be localized
• NSAIDs work for leukemic pain. If have to take NSAIDs around the clock, this is a red flag for bony pain.”
• Discomfort on limb compression,
• “very abnormal” ESR, and absence of thrombocytosis are other signs of bony involvement.

Transient synovitis.

• can be severe and can signal the early phase of Legg-Calvé-Perthes disease, an idiopathic avascular necrosis of the femoral head.
• ESR < 40 mm/hr is diagnostic.
• Synovitis typically lasts 1–3 weeks and can be related to Legg-Calvé-Perthes disease or parvovirus.

Recurrent transient synovitis

• in some pediatric patients could be the onset of psoriasis or spondyloarthropathy,

Intermittent monoarthritis.

• Pediatric patients with intermittent arthritis often have a joint that gets swollen, the inflammation resolves in a few weeks, and then the joint gets swollen again.
• Be patient with these patients. Just wait until the effusion goes away—most of the time it happen.
• A big, bland effusion without a contracture is a presentation that is very suggestive of Lyme arthritis.

Acute monoarthritis

• multiple etiologies
• Septic arthritis is the most important to remember.Septic arthritis is usually monoarticular; exceptions are cases caused by gonococcus or tuberculosis and nontuberculosis mycobacterium.
• Nonpyogenic infection, foreign bodies, pigmented villonodular synovitis, coagulopathy, and vascular abnormalities are other causes of monoarthritis.
• Trauma especially among children who fall on their knees. The pain should not last more than 48 hours.

Migratory arthritis

• primarily intermediate joints, approximately one per day, characterized by periarticular swelling.
• It is a sequential form of “polyarticular monoarthritis,”
• very painful but responsive to NSAIDs.
• Etiology is overwhelmingly postinfectious

Acute polyarticular arthrition

• Parvovirus infection is the most common cause.
• Approximately 1/3 present with an intense red rash in a symmetrical pattern on both hands and feet.
• Small epidemics often occur in springtime.

Rheumatic fever

• fever of 101.3° F daily and an ESR of greater than 50 mm/hr.
• look ill and tachycardia, gallop, and murmurs.
• Echocardiography within the first week for all cases of suspected rheumatic fever.