A Specialist Weighs In: Not All Pediatric Joint Pain Is Due to Growing Pains

The cases presented this month share a common theme: pediatric joint pain. As these 3 cases demonstrate, diagnosing joint pain in children can be quite challenging. Although many cases are attributed to growth-related causes, it is crucial to recognize that not all joint pain in children is due to growth. A thorough evaluation of joint pain requires close attention to detail, as no single sign or symptom clearly defines the underlying cause.The patient’s history and physical examination remain the cornerstones of diagnosis and should never be underestimated. Furthermore, diagnostic laboratory results and imaging only add value when used in conjunction with a comprehensive clinical assessment. I always keep in mind the “triad” of history, physical examination, and imaging (See Figure 1). When these align, a diagnosis is often clear. If 2 out of 3 are inconclusive, the search must continue. This approach emphasizes that a diagnosis should not rely solely on 1 aspect (eg, imaging alone) but rather be a combination of all 3.We have 3 illustrative cases that highlight the diversity of pediatric joint pain presentations. The first case involves a boy who presented to the emergency department with 4 days of left elbow swelling, pain, and erythema. His history revealed a recent upper respiratory infection and a 2-year history of recurrent joint swelling with mild pain in the left knee and/or ankle, without fever, rash, or severe discomfort. Family history was notable for rheumatoid arthritis, Crohn disease, and thyroid disorders. Physical examination showed significant left elbow swelling with limited range of motion. Laboratory results revealed a normal white blood cell (WBC) count, mildly elevated erythrocyte sedimentation rate (ESR), and elevated C-reactive protein (CRP). Imaging revealed a moderate effusion. Two potential causes came to mind: infectious or inflammatory. After performing an arthrocentesis and completing the differential diagnosis, the patient was diagnosed with Lyme arthritis. This case underscores the importance of maintaining a high index of suspicion when evaluating pediatric joint pain.The second case involves a 13-year-old girl with a history of myasthenia gravis and absence epilepsy. She presented with 1 week of right-sided neck swelling and tenderness, along with difficulty swallowing solids. Over the past few months, she had lost approximately 20 kg, experienced bilateral finger pain, and lost the ability to make fists—symptoms she and her mother attributed to her myasthenia gravis. She also reported bilateral knee pain and swelling, which had been diagnosed as patellofemoral pain syndrome. Physical examination revealed a 3-cm mobile mass in the right occipital triangle, tenderness with finger flexion, and reduced grip strength. Laboratory results showed elevated CRP, procalcitonin, ESR, and a low WBC count. After reviewing the medication history and considering the differential diagnosis, she was diagnosed with drug-induced lupus due to a recently prescribed medication. This case highlights the importance of thoroughly reviewing medications in patients with lymphadenopathy and joint pain.The third case is of a 6-year-old girl who presented with nasal congestion, cough, fatigue, dyspnea on exertion, intermittent left ankle pain, and a newly discovered heart murmur. Her musculoskeletal examination did not reveal significant joint-related findings, but laboratory results showed elevated WBC count, anemia, platelets, and inflammatory markers. An echocardiogram revealed severe mitral regurgitation with left atrial dilation and a small pericardial effusion. Based on her clinical presentation, laboratory results, and echocardiogram findings, the diagnosis of acute rheumatic fever with severe carditis was made. This case reminds us to consider acute rheumatic fever as a possible cause of joint pain, particularly in pediatric patients with a recent history of streptococcal infection.These 3 cases highlight the complexity of pediatric joint pain and underscore the need for a meticulous, systematic, and cost-effective approach to evaluation. Clinicians must always take a systematic approach, thoroughly considering all potential diagnoses. I use a mental algorithm mnemonic, “A.R.T.I.C.U.L.A.R,” to systematically rule out potential causes of joint pain:A stands for autoimmune diseases like juvenile idiopathic arthritis or lupus, particularly relevant if there is a family history or if the pain involves multiple joints. R refers to reactive arthritis, which often occurs after infections, such as gastrointestinal or respiratory illnesses. T reminds us always to consider trauma or injury, especially from sports or overuse. I stands for infection, such as septic arthritis or osteomyelitis. C highlights the possibility of cancer. U helps differentiate between unilateral pain, which may suggest trauma or infection, and bilateral pain, which is often associated with systemic disease. L refers to leg discrepancy and limping, as changes in gait could indicate hip disorders like slipped capital femoral epiphysis or Legg-Calvé-Perthes disease. A stands for allergic or drug reactions, such as drug-induced lupus. Finally, R reminds clinicians to consider referred pain and look for associated features. This ensures that nothing is overlooked during the assessment, leading to appropriate diagnostic steps and treatment.In my clinic, I mainly see trauma, infections, malignancy, and rheumatologic and growing pains. When trauma is the suspected cause, the history should indicate constant pain following an injury or sports activity, without fever or weight loss. The pain should limit joint movement, and physical examination should reveal localized tenderness. This diagnosis is confirmed with imaging, such as x-rays or magnetic resonance imaging (MRI); blood work is typically unnecessary. Once confirmed, appropriate treatment can be initiated.If the pain is constant and associated with fever, infection should be the primary consideration. The history should suggest acute-onset pain with fever, and the physical examination should reveal a warm, swollen joint that is tender to movement or palpation. Laboratory results often show elevated WBC counts, with neutrophils predominating in bacterial infections. Viral infections, such as transient synovitis, should be considered when lymphocytic predominance is observed. At this point, it’s crucial to mention the Kocher criteria to differentiate between septic arthritis of the hip, which is an emergency, and transient synovitis. The criteria include an inability to bear weight, a temperature above 38.5 °C (101.3 °F), ESR above 40 mm/h or CRP above 2 mg/dL, and WBC counts above 12 000 cells/mm3. Once laboratory results and imaging confirm an infectious process, treatment can begin.If the patient presents with acute, constant pain and a history of weight loss, malignancy must be considered. The physical examination may reveal localized pain, lymphadenopathy, or weakness, while laboratory results may show anemia, abnormal platelet and WBC counts, and elevated inflammatory markers. Imaging such as x-rays or MRI will help confirm the diagnosis.If the pain is chronic or happens in multiple joints or there’s stiffness in the morning that gets better as the day goes on, I start thinking about rheumatologic conditions. A good history is important here—especially if there’s a family history of autoimmune diseases, or if the patient has other symptoms like rashes. On examination, I’m looking for swelling, warmth, and tenderness, particularly in the small joints of the hands or feet. Blood work is helpful, especially to check for inflammation markers like ESR and CRP, or autoantibodies. Imaging isn’t always necessary right away but can help if there’s concern about joint damage. I’ll refer the patient to a rheumatologist to dig deeper.If the pain occurs predominantly in the evenings after physical activity, is nonmigratory, and is not associated with fever or weight loss, growing pains are likely the cause. However, due to the ambiguity of symptoms, I routinely order basic blood tests (complete blood count, ESR, and CRP). I only request imaging if the pain is localized to a single joint.The author wishes to thank Elyette Lugo, BS.